Wordorigins.org

Strunk, W. and E. B. White (1979). The elements of style. New York, Macmillan.

This is without a doubt the most famous style and usage manual in existence. But despite it’s fame, it is actually not a very good guide. It reflects the authors’ idiosyncratic preferences rather than actual usage and it is rather out of date. E.B. White is a great writer and this book is quite witty and entertaining, so read it for that and not as a reference guide. There are much better usage manuals to be had.