Cite

United States, Contour Map.

MLA

United States, Contour Map. U.S. Geological Survey, 1909. https://collections.library.yale.edu/catalog/15827370.

APA, 6th edition

United States, Contour Map. (1909). [Maps]. U.S. Geological Survey, https://collections.library.yale.edu/catalog/15827370.