I am working on the article describing conversion of people to Vaisnavism before Srila Prabhupada started his mission, going back to ancient times. I've got this idea when I found some nice Vaisnava poetry written by Muslims in brajabuli language (Pada-kalpa-taru). Unfortunately I have hard time finding source texts and mentions about this topic. Do you have some information or links that could be useful? Maybe you know some books that deal with this topic? Thanks.