International Stratigraphic Guide, A guide to Stratigraphic Classification, Terminology, and Procedure Ed. Hollis D. Hedberg, Box: 11, Folder: 45. Hollis Hedberg papers, RH MS 546. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/149307 Accessed November 25, 2024.