I would like to suggest the book "Miracles of Mind: Exploring Nonlocal Consciousness and Spiritual Healing" It's one of the few books of it's type (serious inquiry into the mechanics of healing modalitites) that not only mentions Reiki psecifically but distinguishes energy healing modalities from spiritual healing modalities.
The authors are Russell Targ (a researcher who worked on the govt. remote viewing program) and Jane Katra Ph.D. (a working healer).
