1. Beck, C.B., Connection between Archaeopteris and Callixylon, Science, 1960, vol. 131, pp. 1524–1525.
2. Beck, C.B., Reconstructions of Archaeopteris and Further Consideration of its Phylogenetic Position, Am. J. Bot., 1962, vol. 49, pp. 373–382.
3. Larionova, Z.V., Menner, V.Vl., Tsaplin, A.E., et al., Lower Frasnian Horizons in the Timan-Pechora Province, in Stratigrafiya i paleogeografiya devona, karbona i permi Russkoi platformy (Stratigraphy and Paleogeography of Devonian, Carbon, and Permian of the Russia Platform), Moscow, 1991, pp. 73–77.
4. Lemoigne, Y., Iurina, A., and Snigirevskaya, N., Revision du Genre Callixylon Zalessky, 1911 (Archaeopteris) du Devonien, Palaeontogr. Abt. B., 1983, vol. 186, no. 406, pp. 81–120.
5. Menner, V.Vl., Larionova, Z.V., Araslanova, R.M., et al., New Regional Lower Frasnian Horizons in the Timan-Pechora Province, in Paleontologiya v prakticheskoi stratigrafii (Paleontology in Practical Stratigraphy), Moscow, 1989, pp. 5–12.