MLA
Gonne, Maud, 1866-1953. Letter written by Maud Gonne to William Butler Yeats - December 28 [1902]. December 28, 1902. 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/750tqjq4h4-cor.
APA, 6th edition
Gonne, Maud, 1866-1953. (December 28, 1902)[Letter written by Maud Gonne to William Butler Yeats - December 28 [1902]]. 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/750tqjq4h4-cor.
Chicago
Gonne, Maud, 1866-1953, Letter written by Maud Gonne to William Butler Yeats - December 28 [1902], December 28, 1902, 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/750tqjq4h4-cor.