MLA
Hugh C. Leighton Co. (Portland, Me.). Picking cotton : a large group of African American men, African American women and African American boys picking cotton [hand colored]. unknown. Robert Langmuir African American Photograph Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/081wdbrv47-cor.
APA, 6th edition
Hugh C. Leighton Co. (Portland, Me.). (unknown)[Picking cotton : a large group of African American men, African American women and African American boys picking cotton [hand colored]]. Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/081wdbrv47-cor.
Chicago
Hugh C. Leighton Co. (Portland, Me.), Picking cotton : a large group of African American men, African American women and African American boys picking cotton [hand colored], unknown, Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/081wdbrv47-cor.