Part 1. Purification Through Solitude by Vimala Thakar, J. Krishnamurti, Swami Sivananda.
Part 2. Living In Solitude by Swami Chinmayananda, Swami Tapovan, Dr. Paul Brunton.
Part 3. Solitude Amid The Many by Sri Ramana Maharshi, Thomas Merton, and Thomas R. Kelly.