APA (7th ed.) Citation

Walker, G. W. (1977). Geologic map of Oregon east of the 121st meridian. The Survey.

Chicago Style (17th ed.) Citation

Walker, George Walton. Geologic Map of Oregon East of the 121st Meridian. Reston, Va.: The Survey, 1977.

MLA (9th ed.) Citation

Walker, George Walton. Geologic Map of Oregon East of the 121st Meridian. The Survey, 1977.