MLA
Gonne, Maud, 1866-1953. Letter written by Maud Gonne to William Butler Yeats - [December 1913]. December 1913. 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/098z8w9jnj-cor.
APA, 6th edition
Gonne, Maud, 1866-1953. (December 1913)[Letter written by Maud Gonne to William Butler Yeats - [December 1913]]. 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/098z8w9jnj-cor.
Chicago
Gonne, Maud, 1866-1953, Letter written by Maud Gonne to William Butler Yeats - [December 1913], December 1913, 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/098z8w9jnj-cor.