APA (7th ed.) Citation

United States. Forest Service. (1990). ROS: Primer and field guide. U.S. Dept. of Agriculture, Forest Service.

Chicago Style (17th ed.) Citation

United States. Forest Service. ROS: Primer and Field Guide. [Washington, D.C.?]: U.S. Dept. of Agriculture, Forest Service, 1990.

MLA (8th ed.) Citation

United States. Forest Service. ROS: Primer and Field Guide. U.S. Dept. of Agriculture, Forest Service, 1990.