Friday the 13th

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Friday the 13th in a calendar Freitag der 13. im Kalender.jpg
Friday the 13th in a calendar

Friday the 13th is considered an unlucky day in Western superstition. It occurs when the 13th day of the month in the Gregorian calendar falls on a Friday, which happens at least once every year but can occur up to three times in the same year – for example, in 2015, the 13th fell on a Friday in February, March, and November. 2017 through 2020 will all have two Friday the 13ths, and the years 2021 and 2022 will have just one occurrence each. [1]

Western culture Norms, values and political systems originating in Europe

Western culture, sometimes equated with Western civilization, Occidental culture, the Western world, Western society, and European civilization, is the heritage of social norms, ethical values, traditional customs, belief systems, political systems, artifacts and technologies that originated in or are associated with Europe. The term also applies beyond Europe to countries and cultures whose histories are strongly connected to Europe by immigration, colonization, or influence. For example, Western culture includes countries in the Americas and Australasia, whose language and demographic ethnicity majorities are of European descent. Western culture has its roots in Greco-Roman culture from classical antiquity.

Superstition belief or practice that is considered irrational or supernatural

Superstition is any belief or practice that is considered irrational or supernatural: for example, if it arises from ignorance, a misunderstanding of science or causality, a positive belief in fate or magic, or fear of that which is unknown. It is commonly applied to beliefs and practices surrounding luck, prophecy, and certain spiritual beings, particularly the belief that future events can be foretold by specific (apparently) unrelated prior events. The word superstition is often used to refer to a religion not practiced by the majority of a given society regardless of whether the prevailing religion contains alleged superstitions.

The Gregorian calendar is the calendar used in most of the world. It is named after Pope Gregory XIII, who introduced it in October 1582.

Contents

A Friday the 13th occurs during any month that begins on a Sunday.

History

The irrational fear of the number 13 has been given a scientific name: "triskaidekaphobia"; and on analogy to this the fear of Friday the 13th is called paraskevidekatriaphobia, from the Greek words Paraskeví (Παρασκευή, meaning "Friday"), and dekatreís (δεκατρείς, meaning "thirteen"). [2]

Triskaidekaphobia Fear of the number 13

Triskaidekaphobia is fear or avoidance of the number 13. It is also a reason for the fear of Friday the 13th, called paraskevidekatriaphobia or friggatriskaidekaphobia.

Greek language Language spoken in Greece, Cyprus and Southern Albania

Greek is an independent branch of the Indo-European family of languages, native to Greece, Cyprus and other parts of the Eastern Mediterranean and the Black Sea. It has the longest documented history of any living Indo-European language, spanning more than 3000 years of written records. Its writing system has been the Greek alphabet for the major part of its history; other systems, such as Linear B and the Cypriot syllabary, were used previously. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic, and many other writing systems.

The Last Supper by Leonardo da Vinci Ultima Cena - Da Vinci 5.jpg
The Last Supper by Leonardo da Vinci

The superstition surrounding this day may have arisen in the Middle Ages, "originating from the story of Jesus' last supper and crucifixion" in which there were 13 individuals present in the Upper Room on the 13th of Nisan Maundy Thursday, the night before his death on Good Friday. [3] [4] While there is evidence of both Friday [5] and the number 13 being considered unlucky, there is no record of the two items being referred to as especially unlucky in conjunction before the 19th century. [6] [7] [8]

Middle Ages Period of European history from the 5th to the 15th century

In the history of Europe, the Middle Ages lasted from the 5th to the 15th century. It began with the fall of the Western Roman Empire and merged into the Renaissance and the Age of Discovery. The Middle Ages is the middle period of the three traditional divisions of Western history: classical antiquity, the medieval period, and the modern period. The medieval period is itself subdivided into the Early, High, and Late Middle Ages.

Crucifixion of Jesus Jesus crucifixion as described in the four canonical gospels

The crucifixion of Jesus occurred in 1st-century Judea, most likely between AD 30 and 33. Jesus' crucifixion is described in the four canonical gospels, referred to in the New Testament epistles, attested to by other ancient sources, and is established as a historical event confirmed by non-Christian sources, although there is no consensus among historians on the exact details.

Maundy Thursday Christian holiday commemorating the Last Supper

Maundy Thursday is the Christian holy day falling on the Thursday before Easter. It commemorates the Washing of the Feet (Maundy) and Last Supper of Jesus Christ with the Apostles, as described in the canonical gospels.

An early documented reference in English occurs in Henry Sutherland Edwards' 1869 biography of Gioachino Rossini, who died on a Friday 13th:

Henry Sutherland Edwards (1828–1906) was a British journalist.

Gioachino Rossini 19th-century Italian opera composer

Gioachino Antonio Rossini was an Italian composer who gained fame for his 39 operas, although he also wrote many songs, some chamber music and piano pieces, and some sacred music. He set new standards for both comic and serious opera before retiring from large-scale composition while still in his thirties, at the height of his popularity.

He [Rossini] was surrounded to the last by admiring friends; and if it be true that, like so many Italians, he regarded Fridays as an unlucky day and thirteen as an unlucky number, it is remarkable that on Friday 13th of November he passed away. [9]

Rossini by Henri Grevedon Rossini by Grevedon.jpg
Rossini by Henri Grevedon

It is possible that the publication in 1907 of Thomas W. Lawson's popular novel Friday, the Thirteenth, [10] contributed to disseminating the superstition. In the novel, an unscrupulous broker takes advantage of the superstition to create a Wall Street panic on a Friday the 13th. [6]

Thomas W. Lawson (businessman) American writer

Thomas William Lawson was an American businessman and author. A highly controversial Boston stock promoter, he is known for both his efforts to promote reforms in the stock markets and the fortune he amassed for himself through highly dubious stock manipulations.

A broker is a person or firm who arranges transactions between a buyer and a seller for a commission when the deal is executed. A broker who also acts as a seller or as a buyer becomes a principal party to the deal. Neither role should be confused with that of an agent—one who acts on behalf of a principal party in a deal.

Wall Street Street in Manhattan, New York

Wall Street is an eight-block-long street running roughly northwest to southeast from Broadway to South Street, at the East River, in the Financial District of Lower Manhattan in New York City. Over time, the term has become a metonym for the financial markets of the United States as a whole, the American financial services industry, or New York–based financial interests.

A suggested origin of the superstition—Friday, 13 October 1307, the date Philip IV of France arrested hundreds of the Knights Templar—may not have been formulated until the 20th century. It is mentioned in the 1955 Maurice Druon historical novel The Iron King (Le Roi de fer), John J. Robinson's 1989 work Born in Blood: The Lost Secrets of Freemasonry, Dan Brown's 2003 novel The Da Vinci Code and Steve Berry's The Templar Legacy (2006). [2] [11] [12]

Tuesday the 13th in Hispanic and Greek culture

In Spanish-speaking countries, instead of Friday, Tuesday the 13th (martes trece) is considered a day of bad luck. [13]

The Greeks also consider Tuesday (and especially the 13th) an unlucky day. [14] Tuesday is considered dominated by the influence of Ares, the god of war (Mars in Roman mythology). The fall of Constantinople to the Fourth Crusade occurred on Tuesday, April 13, 1204, and the Fall of Constantinople to the Ottomans happened on Tuesday, 29 May 1453, events that strengthen the superstition about Tuesday. In addition, in Greek the name of the day is Triti (Τρίτη) meaning the third (day of the week), adding weight to the superstition, since bad luck is said to "come in threes". [14]

Tuesday the 13th occurs in a month that begins on a Thursday.

Friday the 17th in Italy

In Italian popular culture, Friday the 17th (and not the 13th) is considered a day of bad luck. [15] The origin of this belief could be traced in the writing of number 17, in Roman numerals: XVII. By shuffling the digits of the number one can easily get the word VIXI ("I have lived", implying death in the present), an omen of bad luck. [16] In fact, in Italy, 13 is generally considered a lucky number. [17] However, due to Americanization, young people consider Friday the 13th unlucky as well. [18]

The 2000 parody film Shriek If You Know What I Did Last Friday the Thirteenth was released in Italy with the title Shriek – Hai impegni per venerdì 17? ("Shriek – Do You Have Something to Do on Friday the 17th?").

Friday the 17th occurs on a month starting on Wednesday.

Social impact

According to the Stress Management Center and Phobia Institute in Asheville, North Carolina, an estimated 17 to 21 million people in the United States are affected by a fear of this day, making it the most feared day and date in history. Some people are so paralyzed by fear that they avoid their normal routines in doing business, taking flights or even getting out of bed. "It's been estimated that [US]$800 or $900 million is lost in business on this day". [7] Despite this, representatives for both Delta Air Lines and Continental Airlines (the latter now merged into United Airlines) have stated that their airlines do not suffer from any noticeable drop in travel on those Fridays. [19]

In Finland, a consortium of governmental and nongovernmental organizations led by the Ministry of Social Affairs and Health promotes the National Accident Day (kansallinen tapaturmapäivä) to raise awareness about automotive safety, which always falls on a Friday the 13th. [20] The event is coordinated by the Finnish Red Cross and has been held since 1995. [21]

Rate of accidents

A study in the British Medical Journal , published in 1993 [22] , attracted some attention from popular science-literature [23] [24] , as it concluded that "'the risk of hospital admission as a result of a transport accident may be increased by as much as 52 percent' on the 13th"; however, the authors clearly state that "the numbers of admissions from accidents are too small to allow meaningful analysis". Subsequent studies have disproved any correlation between Friday the 13th and the rate of accidents [25] [26] .

On the contrary, the Dutch Centre for Insurance Statistics on 12 June 2008 stated that "fewer accidents and reports of fire and theft occur when the 13th of the month falls on a Friday than on other Fridays, because people are preventatively more careful or just stay home. Statistically speaking, driving is slightly safer on Friday the 13th, at least in the Netherlands; in the last two years, Dutch insurers received reports of an average 7,800 traffic accidents each Friday; but the average figure when the 13th fell on a Friday was just 7,500." [27] [28]

Occurrence

In years which begin on the same day of the week and are of the same type (that is, whether they are a common year or leap year), Friday the 13th occurs in the same months.

Months that have a Friday the 13th for each year from 1900 through 2100
MonthYearsYear category Dominical letter
January1905, 1911, 1922, 1928, 1933, 1939, 1950, 1956, 1961, 1967, 1978, 1984, 1989, 1995,
2006, 2012, 2017, 2023, 2034, 2040, 2045, 2051, 2062, 2068, 2073, 2079, 2090, 2096
Common: Sunday, Leap: Sunday A, AG
February1903, 1914, 1920, 1925, 1931, 1942, 1948, 1953, 1959, 1970, 1976, 1981, 1987, 1998,
2004, 2009, 2015, 2026, 2032, 2037, 2043, 2054, 2060, 2065, 2071, 2082, 2088, 2093, 2099
Common: Thursday, Leap: Thursday D, DC
March1903, 1908, 1914, 1925, 1931, 1936, 1942, 1953, 1959, 1964, 1970, 1981, 1987, 1992, 1998,
2009, 2015, 2020, 2026, 2037, 2043, 2048, 2054, 2065, 2071, 2076, 2082, 2093, 2099
Common: Thursday, Leap: Wednesday D, ED
April1900, 1906, 1917, 1923, 1928, 1934, 1945, 1951, 1956, 1962, 1973, 1979, 1984, 1990,
2001, 2007, 2012, 2018, 2029, 2035, 2040, 2046, 2057, 2063, 2068, 2074, 2085, 2091, 2096
Common: Monday, Leap: Sunday G, AG
May1904, 1910, 1921, 1927, 1932, 1938, 1949, 1955, 1960, 1966, 1977, 1983, 1988, 1994,
2005, 2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095
Common: Saturday, Leap: Friday B, CB
June1902, 1913, 1919, 1924, 1930, 1941, 1947, 1952, 1958, 1969, 1975, 1980, 1986, 1997,
2003, 2008, 2014, 2025, 2031, 2036, 2042, 2053, 2059, 2064, 2070, 2081, 2087, 2092, 2098
Common: Wednesday, Leap: Tuesday E, FE
July1900, 1906, 1917, 1923, 1928, 1934, 1945, 1951, 1956, 1962, 1973, 1979, 1984, 1990,
2001, 2007, 2012, 2018, 2029, 2035, 2040, 2046, 2057, 2063, 2068, 2074, 2085, 2091, 2096
Common: Monday, Leap: Sunday G, AG
August1909, 1915, 1920, 1926, 1937, 1943, 1948, 1954, 1965, 1971, 1976, 1982, 1993, 1999,
2004, 2010, 2021, 2027, 2032, 2038, 2049, 2055, 2060, 2066, 2077, 2083, 2088, 2094, 2100
Common: Friday, Leap: Thursday C, DC
September1901, 1907, 1912, 1918, 1929, 1935, 1940, 1946, 1957, 1963, 1968, 1974, 1985, 1991, 1996,
2002, 2013, 2019, 2024, 2030, 2041, 2047, 2052, 2058, 2069, 2075, 2080, 2086, 2097
Common: Tuesday, Leap: Monday F, GF
October1905, 1911, 1916, 1922, 1933, 1939, 1944, 1950, 1961, 1967, 1972, 1978, 1989, 1995,
2000, 2006, 2017, 2023, 2028, 2034, 2045, 2051, 2056, 2062, 2073, 2079, 2084, 2090
Common: Sunday, Leap: Saturday A, BA
November1903, 1908, 1914, 1925, 1931, 1936, 1942, 1953, 1959, 1964, 1970, 1981, 1987, 1992, 1998,
2009, 2015, 2020, 2026, 2037, 2043, 2048, 2054, 2065, 2071, 2076, 2082, 2093, 2099
Common: Thursday, Leap: Wednesday D, ED
December1901, 1907, 1912, 1918, 1929, 1935, 1940, 1946, 1957, 1963, 1968, 1974, 1985, 1991, 1996,
2002, 2013, 2019, 2024, 2030, 2041, 2047, 2052, 2058, 2069, 2075, 2080, 2086, 2097
Common: Tuesday, Leap: Monday F, GF

This sequence, given here for 1900–2099, follows a 28-year cycle from 1 March 1900 to 28 February 2100. The months with a Friday the 13th are determined by the Dominical letter (G, F, GF, etc.) of the year. Any month that starts on a Sunday contains a Friday the 13th, and there is at least one Friday the 13th in every calendar year. There can be as many as three Friday the 13ths in a single calendar year; either in February, March and November in a common year starting on Thursday (such as 2009, 2015 or 2026) (D), or January, April and July in a leap year starting on Sunday (such as 1984, 2012 or 2040) (AG).

The longest period that occurs without a Friday the 13th is 14 months, either from July to September the following year being a common year starting on Tuesday (F) (e.g. 2001-02, 2012-13 and 2018-19), or from August to October the following year being a leap year starting on Saturday (BA) (e.g. 1999-2000 and 2027-28).

The shortest period that occurs with a Friday the 13th is just one month, from February to March in a common year starting on Thursday (D) (e.g. 2009, 2015 and 2026).

Each Gregorian 400-year cycle contains 146,097 days (with 97 leap days) or exactly 20,871 weeks. Therefore, each cycle contains the same pattern of days of the week and thus the same pattern of Fridays that are on the 13th. The 13th day of the month is slightly more likely to be a Friday than any other day of the week. [29] [30] On average, there is a Friday the 13th once every 212.35 days, whereas Thursday the 13th occurs only once every 213.59 days.

Distribution of the 13th day over the 4,800 months
Day of the weekMondayTuesdayWednesdayThursdayFridaySaturdaySunday
Occurrences685685687684688684687

Frequency

In the 2010s, there were three Friday the 13ths in 2012 and 2015, and two in 2013, 2017 and 2018. There will also be two in 2019, with one having already occurred. [1] In the 2020s, there will be three F13s in 2026, and two in 2020, 2023, 2024, and 2029. [1] The rest of years have at least one F13 if there are fewer than two or three in the 2010s and 2020s. [1] Assuming nothing is changed with the calendar, there are never more than three F13s in a year. [31] There is a 28-year cycle that repeats when there is a F13 in February, March and November, and the current start of that pattern was in 2009. [31] Although there is at least one F13 per calendar year, it can be as long as 14 months between two F13s. [32] For the details see the table below.

Year mod 281600 20001700 21001800 22001900 2300Year mod 28
00 06 17 23Jan OctFeb AugJunJan Apr Jul00 06 17 23
01 07 12 18 Jan Apr JulMayFeb Mar NovSep Dec01 07 12 18
02 13 19 24Sep DecJan OctFeb AugJun02 13 19 24
03 08 14 25JunJan Apr JulMayFeb Mar Nov03 08 14 25
09 15 20 26Feb Mar NovSep DecJan OctFeb Aug 09 15 20 26
04 10 21 27Feb AugJunJan Apr JulMay04 10 21 27
05 11 16 22 MayFeb Mar NovSep DecJan Oct05 11 16 22

The table is for the Gregorian calendar and Jan/Feb for leap years.

See also

Related Research Articles

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February 29, also known as leap day or leap year day, is a date added to most years that are divisible by 4, such as 2016, 2020, and 2024. A leap day is added in various solar calendars, including the Gregorian calendar standard in most of the world. Lunisolar calendars instead add a leap or intercalary month.

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Friday is the day of the week between Thursday and Saturday. In countries adopting the "Monday-first" convention it is the fifth day of the week. In countries that adopt the "Sunday-first" convention, it is the sixth and penultimate day of the week. In some other countries, for example the Maldives, Friday is the first day of the weekend, with Saturday the second. In Iran Friday is the last day of the weekend, with Saturday as the first day of the working week. Bahrain, the United Arab Emirates (UAE), Saudi Arabia and Kuwait also followed this convention until they changed to a Friday–Saturday weekend: on 1 September 2006 in Bahrain and the UAE, and a year later in Kuwait. In Iran, Friday and Thursday are weekend days.

Tuesday day of the week

Tuesday is the day of the week between Monday and Wednesday. According to international standard ISO 8601, Monday is the first day of the week and so Tuesday is the second day of the week. According to some commonly used calendars, however, especially in the United States, Sunday is the first day of the week and so Tuesday is the third day of the week. The English name is derived from Old English Tiwesdæg and Middle English Tewesday, meaning "Tīw's Day", the day of Tiw or Týr, the god of single combat, and law and justice in Norse mythology. Tiw was equated with Mars in the interpretatio germanica, and the name of the day is a translation of Latin dies Martis.

A common year starting on Sunday is any non-leap year that begins on Sunday, 1 January, and ends on Sunday, 31 December. Its dominical letter hence is A. The most recent year of such kind was 2017 and the next one will be 2023 in the Gregorian calendar, or, likewise, 2018 and 2029 in the obsolete Julian calendar, see below for more. Any common year that starts on Sunday, Monday or Tuesday has two Friday the 13ths. This common year contains two Friday the 13ths in January and October.

A common year starting on Tuesday is any non-leap year that begins on Tuesday, 1 January, and ends on Tuesday, 31 December. Its dominical letter hence is F. The current year, 2019, is a common year starting on Tuesday in the Gregorian calendar. The last such year was 2013 and the next such year will be 2030, or, likewise, 2014 and 2025 in the obsolete Julian calendar, see below for more. Any common year that starts on Sunday, Monday or Tuesday has two Friday the 13ths. This common year contains two Friday the 13ths in September and December. Leap years starting on Monday share this characteristic. From July of the year that precedes this year until September in this type of year is the longest period that occurs without a Friday the 13th. Leap years starting on Saturday share this characteristic, from August of the common year that precedes it to October in that type of year.

A leap year starting on Monday is any year with 366 days that begins on Monday, 1 January, and ends on Tuesday, 31 December. Its dominical letters hence are GF, such as the years 1720, 1748, 1776, 1816, 1844, 1872, 1912, 1940, 1968, 1996, 2024, 2052, 2080, and 2120 in the Gregorian calendar or, likewise, 2008, 2036, and 2064 in the obsolete Julian calendar. Any leap year that starts on Monday, Wednesday or Thursday has two Friday the 13ths. This leap year contains two Friday the 13ths in September and December. Common years starting on Tuesday share this characteristic.

A common year starting on Thursday is any non-leap year that begins on Thursday, 1 January, and ends on Thursday, 31 December. Its dominical letter hence is D. The most recent year of such kind was 2015 and the next one will be 2026 in the Gregorian calendar or, likewise, 2010 and 2021 in the obsolete Julian calendar, see below for more. This common year contains the most Friday the 13ths; specifically, the months of February, March, and November. Leap years starting on Sunday share this characteristic. From February until March in this type of year is also the shortest period that occurs within a Friday the 13th.

A leap year starting on Saturday is any year with 366 days that begins on Saturday, 1 January, and ends on Sunday, 31 December. Its dominical letters hence are BA, such as the years 1820, 1848, 1876, 1916, 1944, 1972, 2000, 2028, 2056, 2084, 2124, 2152, and 2180 in the Gregorian calendar or, likewise, 2012 and 2040 in the obsolete Julian calendar. In the Gregorian calendar all centennial leap years start on Saturday; the next such year will be 2400, see below for more.

A leap year starting on Thursday is any year with 366 days that begins on Thursday 1 January, and ends on Friday 31 December. Its dominical letters hence are DC, such as the years 1880, 1920, 1948, 1976, 2004, 2032, 2060, and 2088, in the Gregorian calendar or, likewise, 1988, 2016, and 2044 in the obsolete Julian calendar. Any leap year that starts on Monday, Wednesday or Thursday has two Friday the 13ths. This leap year contains two Friday the 13ths in February and August.

A leap year starting on Wednesday is any year with 366 days that begins on Wednesday, 1 January, and ends on Thursday, 31 December. Its dominical letters hence are ED, such as the years 1908, 1936, 1964, 1992, 2020, 2048, 2076, and 2116 in the Gregorian calendar or, likewise, 2004 and 2032 in the obsolete Julian calendar. Any leap year that starts on Monday, Wednesday or Thursday has two Friday the 13ths. This leap year contains two Friday the 13ths in March and November. Common years starting on Thursday share this characteristic, but also have another in February.

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The Tranquility Calendar is a solar calendar proposal for calendar reform proposed by Jeff Siggins in 1989. It is a derivative of the International Fixed Calendar as well as the earlier Positivist Calendar published in 1849 by French philosopher Auguste Comte (1798–1857), providing for a year of 13 months of 28 days each, with one day at the end of each year belonging to no month or week, and a leap day approximately every 4 years.

National Accident Day is a day to raise awareness about automotive safety in the country of Finland. It is chosen to be on Friday the 13th each year, and because there is a least one Friday the 13th per year on the modern Gregorian calendar this is always possible. The event-day was started in 1995. In 2013, NAD was on September 13, and at that time Finland was having about one million reported accidents of which there was 2,800 deaths. Accident day is not limited to automotive accidents however, it is also to bring awareness to increasing safety in workplaces. Another place for increased safety awareness is in the home.

References

  1. 1 2 3 4 "Months and Years having Friday the 13th".
  2. 1 2 Weisstein, Eric W. "Triskaidekaphobia on MathWorld". MathWorld . Retrieved 14 August 2010.
  3. DellaContrada, John (9 February 2004). "Fear of "Friday the 13th may likely have originated from Jesus' Last Supper and Crucifixion", Says UB Anthropologist". University at Buffalo, The State University of New York . Retrieved 13 July 2014. There were 13 people at the table (at the Last Supper) and the 13th was Jesus. The Last Supper was on a Thursday, and the next day was Friday, the day of crucifixion. When '13' and Friday come together, it is a double whammy.
  4. Hartston, Willam (1 June 2007). Encyclopedia of Useless Information. Sourcebooks, Incorporated. p. 365. ISBN   9781402248382. In Christian tradition, fear of Friday the 13th stems from the day of the Crucifixion (Friday) and the number at the Last Supper (13). Despite these origins, the Friday the 13th superstition dates back only to the Middle Ages.
  5. Friday has been considered an unlucky day to undertake journeys or begin new projects at least since the 14th century, as witnessed by Chaucer's Canterbury Tales .
  6. 1 2 Nathaniel Lachenmeyer, 13: The Story of the World's Most Popular Superstition ch. 5 (2004).
  7. 1 2 Roach, John (12 August 2004). "Friday the 13th Phobia Rooted in Ancient History". National Geographic News. Retrieved 29 October 2008.
  8. Clar, Mimi (1957). "Friday the 13th". Western Folklore. 16 (1): 62–63. doi:10.2307/1497075. JSTOR   1497075.
  9. Henry Sutherland Edwards, The Life of Rossini, Blackett, 1869, p.340.
  10. Thomas W. Lawson (31 August 2005). Thomas W. Lawson, Friday, the Thirteenth (1907). Gutenberg.org. Retrieved 13 May 2011.
  11. "Friday the 13th". snopes.com. Retrieved 26 March 2007.
  12. "Why Friday the 13th Is Unlucky". Urbanlegends.about.com. Retrieved 13 May 2011.
  13. Rafael Falcón, Christine Yoder Falcón Salsa: a taste of Hispanic culture, p. 64, Praeger (1998), ISBN   0-275-96121-4
  14. 1 2 Chrysopoulos, Philip (13 October 2015). "Why Superstitious Greeks Fear Tuesday the 13th". Greek Reporter. Retrieved 31 October 2016.
  15. Carlo Grande (17 February 2012). "Venerdì 17 porta davvero sfortuna?". La Stampa (in Italian). Retrieved 31 March 2012.
  16. Nick Harris (15 November 2007). "Bad omen for Italy as their unlucky number comes up". The Independent . Retrieved 15 February 2015.
  17. "Venerdì 13 porta (s)fortuna? Non in Italia" (in Italian). cafebabel.com. Retrieved 31 March 2012.
  18. "Venerdì 13 è un giorno che porta sfortuna – Mara rimanda le nozze con Mezzaroma" (in Italian). Corriere del Mezzogiorno. 1 February 2011. Retrieved 31 March 2012.
  19. Josh Sens, "Some Don't Count on lucky", Via Magazine, January 2004.
  20. "Tapaturmapäivä 13.9.2013: erityisteemana työpaikkojen turvallisuustyö (27.06.2013)" [Accident Day 13 Sep 2013: Special Workplace Safety Work (27 Jun 2013)] (in Finnish). Archived from the original on 29 April 2014. Retrieved 2014-04-28.
  21. "Mikä on Tapaturmapäivä?". www.kotitapaturma.fi (in Finnish). Retrieved 9 January 2018.
  22. Scanlon, T. J.; Luben, R. N.; Scanlon, F. L.; Singleton, N. (18 December 1993). "Is Friday the 13th bad for your health?". BMJ. 307 (6919): 1584–1586. doi:10.1136/bmj.307.6919.1584. ISSN   0959-8138. PMC   1697765 . PMID   8292946.
  23. Melina, Remy (13 January 2012). "Statistically Speaking, Is Friday the 13th Really Unlucky?". Live Science . Retrieved 13 April 2018. For starters, a 1993 study published in the British Medical Journal indicates otherwise. Researchers analyzed the traffic flow and number of injuries from car accidents on the southern section of London's M25 motorway during the five months that the 13th fell on a Friday between 1990 and 1992. They compared these numbers to data collected on Friday the 6th of the same months, and found that although there are consistently fewer vehicles on the road during the 13th — possibly as a result of superstitious people choosing not to drive that day, the researchers proposed — "the risk of hospital admission as a result of a transport accident may be increased by as much as 52 percent" on the 13th.
  24. Atul Gawande (20 March 1998). "When a full moon and a lunar eclipse collide with Friday the 13th, do more accidents really happen?". Slate . Retrieved 13 April 2018. The 1993 study, published in the British Medical Journal, compared hospital admissions for traffic accidents on a Friday the 13th with those on a Friday the 6th in a community outside London. Despite a lower highway traffic volume on the 13th than on the 6th, admissions for traffic accident victims increased 52 percent on the 13th.
  25. Lo, Bruce M.; Visintainer, Catherine M.; Best, Heidi A.; Beydoun, Hind A. (July 2012). "Answering the myth: use of emergency services on Friday the 13th". The American Journal of Emergency Medicine. 30 (6): 886–889. doi:10.1016/j.ajem.2011.06.008. PMID   21855260.
  26. Schuld, Jochen; Slotta, Jan E.; Schuld, Simone; Kollmar, Otto; Schilling, Martin K.; Richter, Sven (1 September 2011). "Popular Belief Meets Surgical Reality: Impact of Lunar Phases, Friday the 13th and Zodiac Signs on Emergency Operations and Intraoperative Blood Loss". World Journal of Surgery. 35 (9): 1945–1949. doi:10.1007/s00268-011-1166-8. ISSN   0364-2313. PMID   21713579.
  27. Mirror.co.uk, "Friday 13th is no longer unlucky".
  28. Editorial, Reuters (13 June 2008). "Friday 13th not more unlucky, Dutch study shows". Reuters.
  29. Bodin, Magnus (13 November 1998). "About the date+day-distribution along the epoch". x42. Retrieved 30 January 2014.
  30. B.H. Brown and Raphael Robinson, "Solution to Problem E36", American Mathematical Monthly, vol. 40, issue 10 (1933), p. 607; Jean Meeus, Mathematical Astronomy Morsels IV, 2007, p. 367.
  31. 1 2 "13 Facts About Friday the 13th".
  32. "Johns Hopkins Magazine".