MLA
Sewell, Ashton L. The Roots of the Universal Negro Convention : Held in the City of New York, August 1st to 31st, 1920 : an Historical Background and Review of the Causes Leading up to the Great Convention of the Negro Peoples of the World. [A.L. Sewell?], 1920. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/6149p8d0ds-cor.
APA, 6th edition
Sewell, A. L. (1920). The roots of the Universal Negro Convention : held in the City of New York, August 1st to 31st, 1920 : an historical background and review of the causes leading up to the great Convention of the Negro Peoples of the World [African American pamphlet., African American publisher., African American author.]. Universal Negro Convention (1920 : New York, N.Y.). [A.L. Sewell?]; Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/6149p8d0ds-cor.
Chicago
Sewell, Ashton L. “The Roots of the Universal Negro Convention : Held in the City of New York, August 1st to 31st, 1920 : an Historical Background and Review of the Causes Leading up to the Great Convention of the Negro Peoples of the World.” African American pamphlet., African American publisher., African American author. African American Imprints Collection. [New York?]: [A.L. Sewell?], 1920. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/6149p8d0ds-cor.