Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
GENERIC THIRD PERSON MASCULINE SINGULAR PRONOUN
Traditional grammars describe the masculine singular pronoun as generic and able to refer to either or both sexes or to neuter objects in sentences such as Everybody put on his coat and hat, even when the people referred to by everybody may include both males and females. Much conservative usage, especially within the older generations, still accepts this practice, but more and more Edited English seeks to use inclusive language instead. See also AGREEMENT OF INDEFINITE PRONOUNS AND OTHER SINGULAR NOMINALS WITH VERBS AND OTHER PRONOUNS; INCLUSIVE LANGUAGE; SEXIST LANGUAGE.
