MLA
McDuffie, S. Douglass. Crossing the Line : a Little Light on a Dark Subject. [publisher not identified], 1913. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3074tmph1t-cor.
APA, 6th edition
McDuffie, S. D. (1913). Crossing the line : a little light on a dark subject [African American author., African American pamphlet.]. [publisher not identified]; Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3074tmph1t-cor.
Chicago
McDuffie, S. Douglass. “Crossing the Line : a Little Light on a Dark Subject.” African American author., African American pamphlet. African American Imprints Collection. Cleveland, Ohio: [publisher not identified], 1913. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3074tmph1t-cor.