Bibliography

Fischel, Walter J. "William Popper (1874-1963) and His Contribution to Islamic Scholarship: In Memoriam." Journal of the American Oriental Society 84, no. 3 (1964): 213–220.
Singer, Isidore, ed., et al. The Jewish Encyclopedia: A Descriptive Record of the History, Religion, Literature, and Customs of the Jewish People from the Earliest Times to the Present Day. Vol. 11 (12 vols.). London, England: Funk & Wagnalls Company, 1901.