I just came upon this book and have found it very clear and to the point. It contains a number of wonderful pointers to the "I Am". It is a collection of 231 quotes, with a short commentary that follows, taken from Sri Nisargadatta Maharaj. A free download is available here:

http://www.holybooks.com/nisargadatta-gita-pradeep-apte/

I hope you find it helpful.

Metta,
Brian.