MLA
Artvue Post Card Co. (New York, N.Y.). Two young men paddling in boats on Laurel Creek, at Camp Conestoga, with another young man getting in a boat. unknown. Robert Langmuir African American Photograph Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/098z8w9gms-cor.
APA, 6th edition
Artvue Post Card Co. (New York, N.Y.). (unknown)[Two young men paddling in boats on Laurel Creek, at Camp Conestoga, with another young man getting in a boat]. Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/098z8w9gms-cor.
Chicago
Artvue Post Card Co. (New York, N.Y.), Two young men paddling in boats on Laurel Creek, at Camp Conestoga, with another young man getting in a boat, unknown, Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/098z8w9gms-cor.