Oestereich, Thomas. "Cadalous." The Catholic Encyclopedia. Vol. 3. New York: Robert Appleton Company, 1908. http://www.newadvent.org/cathen/03128c.htm. Accessed 3 Sept 2014.
In Germany, meanwhile, a revolution had taken place. Anno, the powerful Archbishop of Cologne, had seized the regency, and the Empress Agnes retired to the convent at Fructuaria in Piedmont. Having declared himself against Cadalous, the new regent at the Council of Augsburg, Oct., 1062, secured the appointment of an envoy to be sent to Rome for the purpose of investigating Alexander's election. The envoy, Burchard, Bishop of Halberstadt (Anno's nephew), having pronounced favourably upon the election, Alexander II was recognized as the lawful pontiff, and his rival, Cadalous, excommunicated (1063). The antipope did not, however, abandonhis claims. At a counter-synod held at Parma he hurled back the ban and having gathered about him an armed force, once more proceeded to Rome, where he established himself in the Castle of Sant' Angelo and for more than a year defied the power of Alexander at the Lateran. His cause at length becoming hopeless he fled to hisBishopric of Parma. The Council of Mantua, Pentecost, 1064, practically ended the schism by anathematizing Cadalous and formally declaring Alexander II to be the legitimate successor of St. Peter. Cadalous, however, maintained his pretensions to the day of his death.
JAFFÉ, Regesta PP. Rom. (2nd ed.), I, 593 sq.; WILL, Benzos Panegyrikus auf Heinrich IV (Marburg, 1856); HEFELE, Conciliengesch. (2d ed.), IV, 850-882; FETZER, Voruntersuchungen zu einer Gesch. des Pontifikats Alexanders II (Strasburg, 1887); MUNERATI, Sulle origini dell' antipapa Cadalo (Honorius II) vescovo di Parma in Rivista delle scienze storiche (Pavia, 1906).