The first book is Outside the Gates of Science (why it's time for the paranormal to come in from the cold), by Damien Broderick. This is a comprehensive, accurate and well written examination of psi research by a critically-minded observer of the field who has done his homework.
Broderick is also author of numerous award-winning science fiction novels, and has a PhD in the comparative semiotics of science and literature.
The second is Opening to the Infinite, by Stephan Schwartz. Among other things, this book provides an answer to those who cannot accept the possibility of psi unless it has some pragmatic use. Schwartz's stories about practical applications of remote viewing is worth the price of this book, but he goes beyond that and offers a series of exercises, tips and techniques to allow the serious reader to experiment with remote viewing first-hand.