From Wiktionary, the free dictionary
usage guide (plural usage guides)
- (linguistics, education) A book that explains how to use a standardised language correctly and in keeping with currently accepted style, usually through the explication of what are conservatively viewed as language "errors".
2014, James Lambert, “Diachronic stability in Indian English lexis”, in World Englishes, page 114:
There is also a gap between the general population and the falling-standards bemoaners, usage guide publishers, and language pundits, whether conservative or progressive.