Ultrastructural Studies on Graptolites, 2: The Periderm and Its Derivatives in the GraptoloideaDOI: info:10.5479/si.00810266.22.1Smithsonian Institution48
Urbanek, Adam and Towe, Kenneth M. 1975. Ultrastructural Studies on Graptolites, 2: The Periderm and Its Derivatives in the Graptoloidea. Washington, D.C.: Smithsonian Institution. In Smithsonian Contributions to Paleobiology, 22. https://doi.org/10.5479/si.00810266.22.1.