You can buy all books written by Prash Trivedi from www.asthaprakashan.com . Prash Trivedi is one of the famous astrologer who has written many book on astrology. Here are some books written by Prash Trivedi.
1. Astrology for 21st Century
2. Book of Nakshatras
3. Nakshatra Vichar ( It is kind of translation of Book of Nakshatras in Hindi)
4. P's giTa : ScriPTures for the Now
5. The Rahu Ketu Experience: Everything You Wanted to Know about Rahu and Ketu
He also publish his videos on Youtube.