Elsewhere (on the excellent "Language Log" blog) he recommends two books: for grammar/usage, the Merriam-Webster Concise Dictionary of English Usage; for style,

Elsewhere (on the excellent "Language Log" blog) he recommends two books: for grammar/usage, the Merriam-Webster Concise Dictionary of English Usage; for style, Joseph Williams's "Style: toward clarity and grace". The first recommendation I ever saw for Williams's book, FWIW, was from Richard Gabriel (founder of Lucid Inc., author of the paper commonly but misleadingly known as "worse is better" and of "Patterns of Software", and these days concentrating on poetry rather than software).