Relation of Methane Generation to Under Compacted Shales, Shale Diapirs and Mud Volcanoes, by Hollis D. Hedberg, 1974, Box: 6, Folder: 12. Wallace E. Pratt papers, RH MS 870. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/34132 Accessed February 17, 2025.