1. PALEOBOTANICAL STUDIES IN ARCTIC CANADA: I. ARCHAEOPTERIS FROM ELLESMERE ISLAND
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3. On Callixylon newberryi (Dawson) Elkins et Wieland;Arnold C. A.;Contrib. Mus. Paleontol. Univ. Mich.,1931
4. Observations on fossil plants from the Devonian of eastern North America. IV. Plant remains from the Catskill Delta deposits of northern Pennsylvania and southern New York;Arnold C. A.;Contrib. Mus. Paleontol. Univ. Mich.,1939
5. Barnard D. P. W.1967.Class Progymnospermopsida Beck 1960.InW. B.Harlandet al. [ed.] The fossil record. Chapter 6 Gymnospermophyta. Geol. Soc. Lond. London.