Colorado, minor civil divisions : 1930 / Department of Commerce, Bureau of the Census.
MLA
of the Census, United States. Bureau. Colorado, Minor Civil Divisions : 1930 / Department of Commerce, Bureau of the Census. U.S. Govt. Print. Off., 1934. https://collections.library.yale.edu/catalog/15818452.
APA, 6th edition
of the Census, U. S. B. (1934). Colorado, minor civil divisions : 1930 / Department of Commerce, Bureau of the Census. [Maps]. U.S. Govt. Print. Off., https://collections.library.yale.edu/catalog/15818452.