MLA
National Independent Political League, Washington, and D. C. National Negro American Political League, "What It Is and What It Seeks To Do," Broadside, Washington, D.C., No Date. 1848. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 3, Folder 10. https://digital.library.emory.edu/purl/0515mkkxx8-cor.
APA, 6th edition
National Independent Political League, W., & D. C. (1848). National Negro American Political League, "What it is and What it Seeks To Do," broadside, Washington, D.C., no date (Box 3, Folder 10) [Broadsides (notices)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0515mkkxx8-cor.
Chicago
National Independent Political League, Washington, and D.C. “National Negro American Political League, ‘What It Is and What It Seeks To Do," Broadside, Washington, D.C., No Date.” Broadsides (notices). William H. Scott Family Papers, 1848-1982, 1848. Box 3, Folder 10. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0515mkkxx8-cor.