I'm looking for sources on the history of Vajrayana, including its origins and development in India and Tibet. I'm not familiar with the area, so anything may come. I already know of Sam van Schaik's EarlyTibet blog and I have Ronald M. Davidson's book "Indian Esoteric Buddhism: A Social History of the Tantric Movement", but basically that's all. I'd especially appreciate good summaries and enlightening essays, but as I've said, any good text is OK.
Note: it is not the religious history I'm interested in but the latest academic research.
"While teachers of the middle way, mind only, transcendent wisdom, mantra, and other schools may have their own assertions, the fulfillment of those intentions is the same. There is not a single thing that is not contained within mind."
(Gampopa to Düsum Khyenpa, in "The First Karmapa", KTD Pub, p254)
“If you recognize the world of appearance and existence as the mind, realize the mind itself as empty, and have no grasping at the superiority of your realizations — this is the ultimate view."
(Chegom Dzongpa, in "The Book of Kadam", Wisdom Pub, p609)