Anachoropteris involuta / Calamocarpon insignis (megasporangiate), Box: 2, item: 5, Page: 122. Study of the Middle Pennsylvanian Flora Found in Kansas Coal Balls, RH MS 1259. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/57718 Accessed April 28, 2025.