MLA
Gonne, Maud, 1866-1953. Letter written by Maud Gonne to William Butler Yeats - [March 1911]. March 1911. 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/849t1g1n2d-cor.
APA, 6th edition
Gonne, Maud, 1866-1953. (March 1911)[Letter written by Maud Gonne to William Butler Yeats - [March 1911]]. 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/849t1g1n2d-cor.
Chicago
Gonne, Maud, 1866-1953, Letter written by Maud Gonne to William Butler Yeats - [March 1911], March 1911, 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/849t1g1n2d-cor.