1-Islam - The Straight Path:
Islam Interpreted by Muslims
by Kenneth W. Morgan
http://www.religion-online.org/cgi-bin/relsearchd.dll/showbook?item_id=1656

2- The Reconstruction of Religious Thought in Islam
Dr. Muhammad Iqbal
http://www.yespakistan.com/iqbal/reconstruction/

3-AL-IMAM AL-MAHDI

THE JUST LEADER OF HUMANITY
Ibrahim Amini
Translated by:Dr. Abdulaziz Sachedina
http://al-islam.org/mahdi/nontl/Toc.htm

4-KNOWING GOD
Sayyid Mujtaba Musawi Lari
Translated by: F. J. Goulding
http://home.swipnet.se/islam/books/knowing_god/knowing_god.htm