MLA

of Engineers, United States. War Dept. Corps. Montana Territory / Compiled under Direction of Lieut. Edward Maguire, Corps of Eng'Rs by Prvt. Julius J. Durage, Topog'l. Asst. The Dept.], 1881. https://collections.library.yale.edu/catalog/15814913.

APA, 6th edition

of Engineers, U. S. W. D. C. (1881). Montana Territory / compiled under direction of Lieut. Edward Maguire, Corps of Eng'rs by Prvt. Julius J. Durage, Topog'l. Asst. [Maps]. The Dept.], https://collections.library.yale.edu/catalog/15814913.