Verbatim text: Alston, A. H. G. 1955. The heterophyllous Selaginella of continental North America. Bull. Brit. Mus. (Nat. Hist.), Bot. 1(8): 219--274.
Author: Alston, A.H.G.
Year: 1955
Title: The heterophyllous Selaginella of continental North America
Journal: Bull. Brit. Mus. (Nat. Hist.), Bot
Volume: 1
Pages: 219–274