The Magician's Companion: A Practical and Encyclopedic Guide to Magical and Religious Symbolism (Llewellyn's Sourcebook)
This book is as voluminous as its title, and no matter what type of magic you practice, or even if you just study it, it is an indispensable book with a wealth of useful intelligence on all Eastern and Western forms of magic. Bill Whitcomb also graciously provides contact information for areas that are not covered. Any serious student of magic can appreciate the expense of research time, and this book will help minimize the research, thereby allowing more time for your workings.The Magician's Companionis going to be a well-worn volume on my shelf.