Highly recommended books and Dhamma Talks by various Pa Auk teachers:
Category: What they teach in Pa Auk Centers
Download from Singapore site
http://www.pamc.org.sg/edhamma
A personal recommendation:
Written by Venerable U Revata in accessible English, an overview of what the Buddha taught.
"The Truth Taught by All the Buddhas"
by Venerable U Revata