"The dukes of Normandy and their origin" by The Earl of Onslow - London: Hutchinson and Company, 1945, Box: 25, Volume: 53. Personal papers of Joseph M. Kellogg, PP 237. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/136876 Accessed May 20, 2024.