Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
dates
The day, month, and year are variously styled in the United States and Britain. April 15, 1950, is the most common American style, but these are also widely used: 15 April 1950, 4–15–50, and 4/15/50. (Computers often require a zero to fill in a space when the month has only a single digit, as in 04–15–50.) The British way of expressing the numbers-only styles can be confusing for Americans. It gives the same date as 15–4–50, 15.4.50, or 15/4/50, and whether month or day is being given first is unclear when the day of the month is a number smaller than 13. Another overseas style is occasionally used in North America: 15.iv.50. To show dates from and to, use either a hyphen (printing uses something called an en dash, a mark about twice as long as a hyphen and half the size of an em dash; see DASH)—June–October, 1978; January 1–15, 1990—or the prepositions. Some stylebooks omit the comma between month and year: January[,] 1968; June[,] 1970. For an academic or fiscal year that takes in parts of two calendar years, use a virgule: 1991/92. When you want to refer to a decade or a century, use no apostrophe: the 1800s, the 1930s. You will often abbreviate certain months of the year in correspondence but rarely in other Formal situations: Jan., Feb., Aug., Sept., Oct., Nov., and Dec. The four- and five-letter-named months rarely need abbreviating, but when they do (chiefly in lists and the like, rather than in connected discourse), they may be written Mar., Apr., Jun., Jul., and rarely, Sep. May is almost never abbreviated. Occasionally you’ll need to indicate whether a date is B.C. or A.D. (See A.D. for an account of the newly ventured B.C.E. and C.E. substitutes.) Convention orders these this way: The Roman fabulist Phaedrus lived from about 15 B.C. to about A.D. 50 (or more briefly: ca. 15 B.C.–ca. A.D. 50). A doubtful date uses a question mark: Pericles, 495?–429 B.C. One final caveat: when giving beginning and ending dates, never mix dashes with words—it’s either 1946–1948 or from 1946 to 1948, never from 1946–1948.
