Pretty much everything from the following books is allowed; things from other books is a case by case basis - won't be allowing much from those.

• AD&D PHB
• Complete Book of Dwarves
• Complete Book of Elves
• Complete Book of Gnomes and Halflings
• Complete Fighter's Handbook
• Complete Ranger's Handbook
• Complete Paladin's Handbook
• Complete Wizard's Handbook
• Complete Druid's Handbook
• Complete Thief's Handbook
• Complete Bard's Handbook
• Complete Psionics Handbook
• Tome of Magic
• Complete Book of Humanoids
• Faiths and Avatars
• Powers and Pantheons
• Demihuman Deities