MLA
Souvenir Post Card Co. (N.Y.). Cotton picking : a group of African American men, African American women and African American children picking cotton along a path through a cotton field [hand colored]. unknown. Robert Langmuir African American Photograph Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/617qnk98ww-cor.
APA, 6th edition
Souvenir Post Card Co. (N.Y.). (unknown)[Cotton picking : a group of African American men, African American women and African American children picking cotton along a path through a cotton field [hand colored]]. Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/617qnk98ww-cor.
Chicago
Souvenir Post Card Co. (N.Y.), Cotton picking : a group of African American men, African American women and African American children picking cotton along a path through a cotton field [hand colored], unknown, Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/617qnk98ww-cor.