MLA
Hugh C. Leighton Co., Manufacturers (Portland, Me.). Concord, Mass., tablet to John Jack. unknown. Robert Langmuir African American Photograph Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/8128931zgj-cor.
APA, 6th edition
Hugh C. Leighton Co., Manufacturers (Portland, Me.). (unknown)[Concord, Mass., tablet to John Jack]. Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/8128931zgj-cor.
Chicago
Hugh C. Leighton Co., Manufacturers (Portland, Me.), Concord, Mass., tablet to John Jack, unknown, Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/8128931zgj-cor.