Ferns from the Chinle formation (upper Triassic) in the Fort Wingate area, New Mexico /
by Sidney R. Ash.
-- Washington : United States Government Printing Office, 1969
- 52 p., [2] h. de lam. --
(Geological Survey Professional Paper ; 613-D).
Helechos fósiles Nuevo Mexico Paleobotánica Triásico