I have a textbook called “prescriptions for natural health a-z” that I use for pretty much every health problem I’ve ever had, and used it constantly as a holistic nutritionist.
Is that the kind of book you’re looking for?
I’m a registered dietitian and here are the books I’d recommend based on what was given to us throughout our curriculum. This book while outdated is considered the bible of nutrition textbooks. We also used this book, and this book.