Cardiocarpon spinatus (big seed) / Conostoma sp. (small seed), Box: 2, item: 5, Page: 31. 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/57627 Accessed April 18, 2025.