APA (7th ed.) Citation

Little, E. L., & Critchfield, W. B. (1969). Subdivisions of the genus Pinus (pines). US Dep. of Agriculture.

Chicago Style (17th ed.) Citation

Little, Elbert Luther, and William Burke Critchfield. Subdivisions of the Genus Pinus (pines). Washington, DC: US Dep. of Agriculture, 1969.

MLA (9th ed.) Citation

Little, Elbert Luther, and William Burke Critchfield. Subdivisions of the Genus Pinus (pines). US Dep. of Agriculture, 1969.