The Story of the Mahatma Letters (1946) by C. Jinarajadasa
Further interesting information about the Mahatma Letters with fill-in background and quotes from letters. A large number of personages are mentioned from H.P Blavatsky, Col Olcott, A P Sinnett, Mary Neff, Annie Besant, CW Leadbeater, AT Barker, Eliphas Levi, Subba Row, C Jinarajadasa and of course a number of Masters of the Wisdom.