Previté-Orton, Early History, pp. 205, 231; Patrone, 'Agnese'; Creber, Alison (22 April 2019). "Breaking Up Is Hard To Do: Dissolving Royal and Noble Marriages in Eleventh-Century Germany". German History. 37 (2): 149–171. doi:10.1093/gerhis/ghy108. ISSN0266-3554..
worldcat.org
Previté-Orton, Early History, pp. 205, 231; Patrone, 'Agnese'; Creber, Alison (22 April 2019). "Breaking Up Is Hard To Do: Dissolving Royal and Noble Marriages in Eleventh-Century Germany". German History. 37 (2): 149–171. doi:10.1093/gerhis/ghy108. ISSN0266-3554..