MLA

of the Census, United States. Bureau. Wyoming, Minor Civil Divisions : 1930 / Department of Commerce, Bureau of the Census. U.S. Govt. Print. Off., 1934. https://collections.library.yale.edu/catalog/15818382.

APA, 6th edition

of the Census, U. S. B. (1934). Wyoming, minor civil divisions : 1930 / Department of Commerce, Bureau of the Census. [Maps]. U.S. Govt. Print. Off., https://collections.library.yale.edu/catalog/15818382.