Catholic Encyclopedia: Pope Sergius III
Article on the life and papacy of Sergius III.
Ecole Glossary: Sergius III
Brief history of the papacy of Sergius III, by Karen Rae Keck.
Patron Saints Index: Pope Sergius III
Brief illustrated profile.
Popes Through the Ages: Sergius III
History and analysis of the papacy of Sergius III, from the book by Joseph Brusher.