MLA
Open Letter to President McKinley by Colored People of Massachusetts. [publisher not identified], 1899. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/873pvmcwj9-cor.
APA, 6th edition
Open letter to President McKinley by colored people of Massachusetts. (1899). [African American pamphlet., African American author.]. [publisher not identified]; Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/873pvmcwj9-cor.
Chicago
“Open Letter to President McKinley by Colored People of Massachusetts.” African American pamphlet., African American author. African American Imprints Collection. [Boston?]: [publisher not identified], 1899. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/873pvmcwj9-cor.