Linda Howe

Akasha is a Sanskrit word, and means [p]rimary substance, that out of which all things are formed.... It is the first stage of the crystallization of spirit.... This Akashic, or primary substance, is of exquisite fineness and is so sensitive that the slightest vibrations of an ether any place in the Universe register an indelible impression upon it.

The first is by Robert Chaney, the founder of the Astara Foundation, a metaphysical-wisdom school in California. His book, Akashic Records: Past Lives & New Directions

The second book is by Kevin Todeschi of the Association for Research and Enlightenment (A.R.E.