Foundations of Tibetan Mysticism - According to the Esoteric Teachings of the Great Mantra Om Mani Padme Hum. Photographic Plates by Li Gotami. Rider. 1973.

A complete explanation of the esoteric principles of Mantra that also clarifies the differences between Hindu and Tibetan yoga. Translated into many languages, this is an important text for any student of Buddhism. With bibliography, index, and illustrations.