Tittmann, O. H. 1. (1918). Joint maps of the international boundary between United States and Canada along the 141st meridian from the Arctic Ocean to Mt. St. Elias. [Washington]: Dept. of State.

Tittmann, O. H. 1850-1938. Joint Maps of the International Boundary between United States and Canada Along the 141st Meridian From the Arctic Ocean to Mt. St. Elias. [Washington]: Dept. of State, 1918.

Tittmann, O. H. 1850-1938. Joint Maps of the International Boundary between United States and Canada Along the 141st Meridian From the Arctic Ocean to Mt. St. Elias. [Washington]: Dept. of State, 1918.