Bill Drake – The Cultivators Handbook of Marijuana The old standard. Not the most recommended.

Karl Hillig and Paul G. Mahlberg Indiana University A chemotaxonomic analysis of cannabinoid variation in Cannabis (Cannabaceae) -- Hillig and Mahlberg 91 (6) 966 -- American Journal of Botany_files

Sister Mary Etienne Tibeau  1933  -The God Mother of us all.  We owe our all to this lady.

DJ Shorts A very informative writing.

Jorge Cervantes A bit from his book.

Robert Connell Clarke This is the most informative reading you can get. Get a huge preview here (4 chapters), then buy the book.