Elements of Style - William Strunk Jr., E.B. White, Allyn & Bacon
ISBN 020530902X (alternate, search)
I. ELEMENTARY RULES OF USAGE.
1. Form the Possessive Singular of Nouns by Adding 's.
2. In a Series of Three or More Terms with a Single Conjunction, Use a Comma after Each Term except the Last.
3. Enclose Parenthetic Expressions between Commas.
4. Place a Comma before a Conjunction Introducing an Independent Clause.
5. Do Not Join In..