Assalamulaikaum,

There's lots of good info and research done on this subject by Amjad Moiz.

I am posting a few of the links here:

http://www.understanding-islam.com/r...ussion&did=307

http://www.understanding-islam.com/r...estion&qid=375

http://www.understanding-islam.com/r...ussion&did=293


Scholar: Moiz Amjad
Al Mawrid Institue
January 8, 2002

http://www.al-mawrid.org/pages/resea...?research_id=1