As for writers, I am a big fan of Maria Groves approach to herbalism. I also have benefited a lot from reading David Winston, Michael Castleman, and David Hoffman amongst other writers. I recommend the following text books for further study:
1. Groves, Maria. Body into Balance. Storey Publishing, 2016.
This book is great, it works as a DIY herbalism book more than anything else I have seen, but also suited for anyone really. I like her approach.
2. The New Healing Herbs, Michael Castleman
This is a very good A-Z of herbs from around the world. It also has an excellent history of worldwide herbalism section.
Castleman, Michael. “The new healing herbs.” Bantam Book, New York (2001): 465-471.
3. Adaptogens: Herbs for Strength, Stamina, and Stress Relief, Winston and Maimes.
Surely one of the most important herbalism books written in modern times. It includes both rasayana and chinese superior tonics, then also nervines and nootropics. Goes well with ‘Body Into Balance’ by Maria Groves.
Winston, David, and Steven Maimes. Adaptogens: herbs for strength, stamina, and stress relief. Inner Traditions/Bear & Co, 2007.
4. Herbal Therapy and Supplements: A Scientific and Traditional Approach, Merrily and Winston.
This is a very good pocket size dictionary of many different herbs, it has detailed safety information and also a good formulas section in the back.
Kuhn, Merrily A., and David Winston. Winston & Kuhn’s Herbal Therapy and Supplements: A Scientific and Traditional Approach. Lippincott Williams & Wilkins, 2012.
5. Holistic Herbal, David Hoffman
A very strong Western herbalism book, with details of actions, affinities, formulas, conditions, and dosage information. I have a lot of respect for what this man did.
Hoffman, David. Holistic herbal. Element Books, 1988.