Yoga as philosophy and religion

An Introduction to Yoga

A Series of Lessons in Raja Yoga

A History of Indian Philosophy, Volume 1

Mystic Christianity; Or, The Inner Teachings of the Master

The Doctrine and Practice of Yoga Including the Practices and Exercises of Concentration, both Objective and Subjective, and Active and Passive Mentation, an Elucidation of Maya, Guru Worship, and the Worship of the Terrible, also the Mystery of Will-Force

The Hindu-Yogi Science of Breath