Back in the day, us mature (vs. old) members relied on Bill Phillips' Anabolic Reference Guide. In this day and age, I would probably get a basic primer on aas usage from William Llewellyn and then also get Beyond Steroids (for hGH, IGF, etc.) from Anthony Roberts.
Also, for sure, get Legal Muscle from Rick Collins. Besides the law, he also has a primer on anabolics specifically in the book. It's all fun and games until someone gets caught. Once you are in "the system" you are always in the system. You are only a first time offender once! Be careful, know the law, know the implications of possession, get Legal Muscle from Rick Collins.