Operators manual :
helicopter, observation OH-6A.

APA Citation

United States. Department of the Army. (1990). Operators manual: helicopter, observation OH-6A. [Washington, DC]: Headquarters, Dept. of the Army.

MLA Citation

United States. Department of the Army. Operators Manual: Helicopter, Observation OH-6A. [Washington, DC]: Headquarters, Dept. of the Army, 1990.

Warning: These citations may not always be complete (especially for serials).