Primary Sources:
M. K. Gandhi Resource Page
Sri Aurobindo Ghose Resource Page
Rabindranath Tagore: The Religion of Man
Swami Vivekananda: Bhakti Yoga
Swami Vivekananda: Lectures from Colombo to Almora (1944)
Swami Vivekananda: Karma Yoga and Bhakti Yoga (1945)
The Life of Swami Vivekananda
J.H. Woods, trans: The Yoga System of Patanjali (1927)
Swami Prabhavananda: The Eternal Companion (1944)
Life of Sri Ramakrishna
Swami Nikhilananda: hinduism: Its Meaning for the Liberation of the Spirit
M. Eliade: Yoga (1936)