Other
Douglas Crockford: Elements of Style
Renowned handbook of style by William Strunk, Jr. It includes sections on usage, principles of composition, frequently misused words, and frequently misspelled words, L.9-10.3a Standard Format
Bartleby
Bartleby.com: Strunk's the Elements of Style
Bartleby.com's online version of William Strunk, Jr.'s classic reference book, "The Elements of Style."