XXI Int. Geol. Congress, Copenhagen, Denmark. The General Secretary, Mineralogisk Museum, August 15-25, 1960, Box: 61, Folder: 6. Hollis Hedberg papers, RH MS 546. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/150837 Accessed June 01, 2024.