Source: https://www.amazon.com/Way-Herbs-Updated-Developments-Science/dp/0671023276/ref=as_li_ss_tl?ie=UTF8&qid=1488760250&sr=8-1&keywords=The+Way+of+Herbs,+Michael+Tierra&linkCode=ll1&tag=mommypotamus-20&linkId=fdc73dd96495e4f10fde00a5e7ca9025