AAPG "Stratigraphic Correlation and Superpositional Procedures" by J.R. Patterson, May-June 1981, Box: 48, Folder: 21. Hollis Hedberg papers, RH MS 546. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/150462 Accessed June 01, 2024.