I'd add a book by A.C. Bhaktivedanta a/k/a Swami Prabhupada, but I can't find the one I read.
Note: Sometimes I buy first and do my research later to validate my purchase. That's what I did then: I received Knowledge and tried to validate it later. I read Be Here Now, The Acquarian Gospel, The Impersonal Life, Praphupada, Hope for the Flowers and one other.
My point is that it's different reading through the filter of Knowledge with a biased perspective after-the-fact looking for vague references to divine light, celestial harmony, the word and mana from Heaven. They all proved that Guru Maharaji was undoubtedly, irrefutably and definitely for sure the Perfect Master of our time.