Note I am not endorsing any of these books in particular nor the service or pricing of Amazon
A Guide to LATEX: Document Preparation for Beginners and Advanced Users
by Helmut Kopka, Patrick W. Daly
The Latex Companion
by Michel Goossens, Frank Mittelbach (Contributor), Alexander Samarin (Contributor)
LaTeX : A Documentation Preparation System User's Guide and Reference Manual
by Leslie Lamport, Duane Bibby (Illustrator)
Last modified 18 Jan 2000