Samuel Sagan wrote a number of books explaining and detailing meditation topics in great detail. For those interested in IST I recommend two books.
Firstly ‘Awakening the Third Eye’ which describes in great detail both technically and theoretically this initial meditation.
Secondly ‘Regression, Past-life Therapy for Here and Now Freedom’ which details the theory behind the IST sourcing technique with many colourful examples.
As well as his technical books, Samuel also wrote an anthology called Atlantean Secrets. This series of books describes spiritual awakening through the metaphor of a legend.
For a full list see https://clairvision.org/books/index.html
Additionally many of these books can be purchased at the following places: