My three favorite books are for writing. They sit beside my laptop, every ready, ever helpful. Like best friends.
Writer's Digest Flip Dictionary, by Barbara Ann Kipfer, Ph.D. (For when you know what you want to say but can't think of the word.)
Webster's II New College Dictionary, Third Edition
English Through the Ages, by William Brohaugh (From Old English to modern-day slang, a word-by-word birth record of thousands of interesting words.)
The Flip Dictionay is a thesaurus