Grammar Girl's 101 Misused Words You'll Never Confuse Again (Quick & Dirty Tips)
Grammar Girl's Quick and Dirty Tips for Better Writing (Quick & Dirty Tips)
The Blue Book of Grammar and Punctuation: An Easy-to-Use Guide with Clear Rules, Real-World Examples, and Reproducible Quizzes
The Grammar Devotional: Daily Tips for Successful Writing from Grammar Girl (TM) (Quick & Dirty Tips)
Fowler's Dictionary of Modern English Usage
Grammar Girl's 101 Words to Sound Smart (Quick & Dirty Tips)
Grammar Girl's 101 Troublesome Words You'll Master in No Time (Quick & Dirty Tips)
Grammar and Usage in the Classroom (2nd Edition)
The Chicago Guide to Fact-Checking (Chicago Guides to Writing, Editing, and Publishing)
Garner's Modern English Usage