Primordial Experience: An Itroduction to rDzogs-chen Meditation, by Manusrimitra, transl. Namkhai Norbu and Kennard Lipman

An Introduction to rDzogs-chen Meditation: but much more:
Translation and commentary of a Text from Manusrimitra rDo  la gser zhun, "Gold refined from ore"
a little big treasure! personal recommendation!