MLA
International Post Card Co. (N.Y.). Plaza School in Fort Scott, Kans. : a group of men, women and children outside. unknown. Robert Langmuir African American Photograph Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/245q83bk6v-cor.
APA, 6th edition
International Post Card Co. (N.Y.). (unknown)[Plaza School in Fort Scott, Kans. : a group of men, women and children outside]. Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/245q83bk6v-cor.
Chicago
International Post Card Co. (N.Y.), Plaza School in Fort Scott, Kans. : a group of men, women and children outside, unknown, Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/245q83bk6v-cor.