*[http://web.archive.org/web/20080516185655/http://answering-islam.org.uk/Books/Tisdall/Sources0/p011-012.htm Jewish Sources of the Qur'an]
*[http://web.archive.org/web/2007081422085520061012111723/http://www.answering-islam.org.uk/Books/Tisdall/Sources/chapt3.htm Influence of Sabian and Jewish ideas and practices.]