MLA

Stettler, R. F. (Reinhard Friedrich), 1929-, J. C Cummings, and U.S. International Biological Program. Coniferous Forest Biome. A Guide to Forest-tree Collections of Known Source of Parentage In the Western United States and Canada : Results of a Preliminary Survey. : Seattle : Coniferous Forest Biome, Ecosystem Analysis Studies, U.S./International Biological Program, 1973.