A Collection of Biographies of 4 Kriya Yoga Gurus by Swami Satyananda Giri: Yogiraj Shyama Charan Lahiri Mahasay, Yogacharya Shastri Mahasaya (Hansaswami Kebalanandaji Maharaj), Swami Sri Yukteshvar Giri Maharaj, Yogananda Sanga [Paramhansa Yoganandaji As I have Seen and Understood Him]
