MLA
Artvue Post Card Co. (New York, N.Y.). Boys and young men posing in front of a sign for the Sherwood Youth Camp, in Dahinda, Illinois. unknown. Robert Langmuir African American Photograph Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/12683bk3nd-cor.
APA, 6th edition
Artvue Post Card Co. (New York, N.Y.). (unknown)[Boys and young men posing in front of a sign for the Sherwood Youth Camp, in Dahinda, Illinois]. Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/12683bk3nd-cor.
Chicago
Artvue Post Card Co. (New York, N.Y.), Boys and young men posing in front of a sign for the Sherwood Youth Camp, in Dahinda, Illinois, unknown, Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/12683bk3nd-cor.