Dates & Years
Full dates with a year should use the abbreviated written month. Dates without a year should use the full written month. Do not include an ordinal with the number.
Dec. 13, 2010 or December 13
In prose, year ranges in the same decade may omit the first two digits in the second year. In headings or year ranges spanning two different decades must use all four digits for both years. When using multiple date ranges in a paragraph, be consistent, defaulting to using all four digits for both years if there could be a mixture.
1973-1977 and 1977-2011
1973-77 and 1977-2011