For Gymnocarpium
Kramer, K.U., and P.S. Green. 1990. Pteridophytes and Gymnosperms. In K. Kubitzki, ed., The families and genera of vascular plants. Springer-Verlag, Berlin.
Pryer, K.M. 1992. The status of Gymnocarpium heterosporum and G. robertianum in Pennsylvania. Amer. Fern J. 82: 34-39.
Pryer, K.M. 1993. Gymnocarpium. In Flora of North America Editorial Committee. 1993b. Flora of North America north of Mexico. Volume 2, pteridophytes and gymnosperms. Oxford Univ. Press, New York, NY. 475 pp.
Pryer, K.M., and C.H. Haufler. 1993. Isozymic and chromosomal evidence for the allotetraploid origin of Gymnocarpium dryopteris (Dryopteridaceae). Syst. Bot. 18: 150-172.
Rothfels, C.J., A.K. Johnson, M.D. Windham, and K.M. Pryer. 2014. Low-copy nuclear data confirm rampant allopolyploidy in the Cystopteridaceae (Polypodiales). Taxon 63: 1026-1036.
Wang & Pryer in FoC (2013)