Cite

Map of a reconnaissance of the Black Hills, July and August, 1874, with troops under command of Lt. Col. G.A. Custer, 7th Cavalry / by Capt. Wm. Ludlow, Corps of Engineers.

MLA

Ludlow, William, 1843-1901. Map of a reconnaissance of the Black Hills, July and August, 1874, with troops under command of Lt. Col. G.A. Custer, 7th Cavalry / by Capt. Wm. Ludlow, Corps of Engineers.. BRBL_00566. [1874?]. https://collections.library.yale.edu/catalog/15814716.

APA, 6th edition

Ludlow, William, 1843-1901. (["BRBL_00566"])([1874?])[Map of a reconnaissance of the Black Hills, July and August, 1874, with troops under command of Lt. Col. G.A. Custer, 7th Cavalry / by Capt. Wm. Ludlow, Corps of Engineers.]. https://collections.library.yale.edu/catalog/15814716.