MLA

Bachelder, John B. (John Badger), 1825-1894. Map of the battle field of Gettysburg, July 1st, 2nd, 3rd 1863. ; Second day's battle.. BRBL_00502. 1876. https://collections.library.yale.edu/catalog/15811151.

APA, 6th edition

Bachelder, John B. (John Badger), 1825-1894. (["BRBL_00502"])(1876)[Map of the battle field of Gettysburg, July 1st, 2nd, 3rd 1863. ; Second day's battle.]. https://collections.library.yale.edu/catalog/15811151.