Cite

Gen. Merritt's H.Q. at the Rock of the Cross

MLA

Gen. Merritt's H.Q. at the Rock of the Cross. 0AD. https://collections.library.yale.edu/catalog/2014648.

APA, 6th edition

Gen. Merritt's H.Q. at the Rock of the Cross. (0 C.E.). [Albumen prints, Card photographs, Photographic prints, Photographs]. https://collections.library.yale.edu/catalog/2014648.