APA (7th ed.) Citation
Spencer, R., & Jansen, J. J. G. (2012). Did Muhammad exist?: An inquiry into Islam's obscure origins. ISI Books.
Chicago Style (17th ed.) Citation
Spencer, Robert, and Johannes J. G. Jansen. Did Muhammad Exist?: An Inquiry into Islam's Obscure Origins. Wilmington, Delaware: ISI Books, 2012.
MLA (9th ed.) Citation
Spencer, Robert, and Johannes J. G. Jansen. Did Muhammad Exist?: An Inquiry into Islam's Obscure Origins. ISI Books, 2012.
Warning: These citations may not always be 100% accurate.