Wrong: 14 January, 1990
Why: There's a comma between the month and year in a "European style" date.
Right: 14 January 1990
Why: People who have grown up in the United States are used to placing a comma before the year (January 14, 1990). So they're tempted to do the same if they move to the increasingly common European method. In this method, though, in which the day comes first, the month second and the year third (most to least specific), no comma is needed, perhaps because the two numbers are separated by a word, eliminating any chance of numeral confusion.
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