"The Russian primary chronicle" by Samuel H. Cross and Olgord R. Sherbowitz-Wetzer - Cambridge, Massachusetts: The Mediaeval Academy of America, (date unknown), Box: 25, Volume: 52. Personal papers of Joseph M. Kellogg, PP 237. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/136875 Accessed January 18, 2025.