Ultrastructural Studies on Graptolites, 1: The Periderm and Its Derivatives in the Dendroidea and in DOI: info:10.5479/si.00810266.20.1Smithsonian Institution48
Urbanek, Adam and Towe, Kenneth M. 1974. Ultrastructural Studies on Graptolites, 1: The Periderm and Its Derivatives in the Dendroidea and in Mastigograptus. Washington, D.C.: Smithsonian Institution. In Smithsonian Contributions to Paleobiology, 20. https://doi.org/10.5479/si.00810266.20.1.