German Wikipedia, viewed January 14, 2014 (Adolar Zumkeller; Adolar Zumkeller OSA; born June 3, 1915, in Erfurt; died April 21, 2011, in Würzburg; German Augustinian and prominent historian of the order)
Mainpost, April 23, 2011, viewed online on January 14, 2014 link to Traueranzeigen page (P. Dr. Dr. Adolar (Walter) Zumkeller OSA; died April 21, 2011, at age 96; scholar of the works of Saint Augustine and the history of the Augustinian order)
Theology and history of the Augustinian Order in the Middle Ages, 1996 CIP data sheet (born June 3, 1915)