MLA

United States. Army Service Schools (Fort Leavenworth, Kan.). Topographical map, Gettysburg, Antietam / Engineer. Dept., Army Service Schools.. BRBL_00499. 1913. https://collections.library.yale.edu/catalog/15827665.

APA, 6th edition

United States. Army Service Schools (Fort Leavenworth, Kan.). (["BRBL_00499"])(1913)[Topographical map, Gettysburg, Antietam / Engineer. Dept., Army Service Schools.]. https://collections.library.yale.edu/catalog/15827665.