Verbatim text: Little, E.L. Jr. 1952. The genus Pseudotsuga (Douglas-fir) in North America. Leafl. W. Bot. 6: 181--198.
Author: Little, E.L. Jr.
Year: 1952
Title: The genus Pseudotsuga (Douglas-fir) in North America
Journal: Leafl. W. Bot
Volume: 6
Pages: 181–198