Dear Dr. Shabbir,
Thank you for your quick response and I apologize for killing the thread.
My sources would obviously be ahadith and any of the mainstream biographies of the prophet. I then understand that you are leaning towards an argument where you deny that he ever married more than four women at the same time, since is not in the Quran.
I do respectfully ask whether you do have any more knowledge about the number and the wives of his marriages after Khadija, other than that he had no more than 4 at a time.