Handbook for Preclears (December 1951): This book is a companion to Advanced Procedure and Axioms. Handbook for Preclears contains 15 Acts of self-processing that parallel the Fifteen Acts in APA. HFP contains explanations for such situations as why behavior patterns become fixed, why habits seemingly persist and why decisions...

Have You Lived Before This Life? (1960): This book details 41 case histories of people addressing past lives in the Fifth London Advanced Clinical Course in 1958. This book claims to be the first book of it's kind — detailing from the recesses of human memory exactly what happens...

This book is not currently in print by the Church, but it was the first, I believe to present the concept of a "communicator." The system was used by LRH in the 1950s and beyond. Earlier editions (used) can be found online.