Modern Essentials Handbook (12th Edition)
Modern Essentials is a complete guide (over 400 pages) to using essential oils. Very practical with general information about the various applications, explanation per oil and an extensive reference book in which you can easily look up which oil/oils you can use to support certain complaints/symptoms.
N.B. The Modern Essentials book is commonly used by people who work with dōTERRA branded oils, although the book is written brand neutral and can be applied to and used as a reference for various brands.