MLA
Gonne, Maud, 1866-1953. Postcard written by Maud Gonne to William Butler Yeats - November 8, 1920. November 1920. Maud Gonne and W.B. Yeats Papers, circa 1890-1938. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/873pvmcxv3-cor.
APA, 6th edition
Gonne, Maud, 1866-1953. (November 1920)[Postcard written by Maud Gonne to William Butler Yeats - November 8, 1920]. Maud Gonne and W.B. Yeats Papers, circa 1890-1938, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/873pvmcxv3-cor.
Chicago
Gonne, Maud, 1866-1953, Postcard written by Maud Gonne to William Butler Yeats - November 8, 1920, November 1920, Maud Gonne and W.B. Yeats Papers, circa 1890-1938, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/873pvmcxv3-cor.