music theory

What is a good book or get to a site about music theory and / or history?

I would like more information on music theory and history, but do not know what a reliable source.

This is one of the best sources of theory http://www.tonalityguide.com/tableofcontents.php I know this is a music appreciation Directory http://www.gti.net/mocolib1/music/bach.html

Music Theory 101 — The Treble Clef — from ilearnmusic.com