天主教百科全书. New York: Robert Appleton Company. 1913. Paschal Robinson. Chronological Lists of Popes. 天主教百科全书. New York: Robert Appleton Company. 1913. Paschal
ISBN 978-0-393-32056-5 (英语) Wilson, James Grant; Fiske, John, Appleton's Cyclopedia of American Biography, New York: D. Appleton and Company, 1959 (英语)
B. Ecclesiastical Letters. The Catholic Encyclopedia. New York: Robert Appleton Company. 1910 [2018-02-08]. (原始内容存档于2018-02-08) –通过New Advent (英语). Thurston