MLA
Howe, F. L. Who's a Nigger : Two African American Boys Fist Fighting and Several Surrounding Them Watching. 1895. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 73. https://digital.library.emory.edu/purl/187pnvx0nf-cor.
APA, 6th edition
Howe, F. L. (1895). Who's a nigger : two African American boys fist fighting and several surrounding them watching (Box 73) [Postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/187pnvx0nf-cor.
Chicago
Howe, F. L. “Who's a Nigger : Two African American Boys Fist Fighting and Several Surrounding Them Watching.” Postcards. Robert Langmuir African American Photograph Collection, 1895. Box 73. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/187pnvx0nf-cor.