MLA
Gonne, Maud, 1866-1953. Letter written by Maud Gonne to William Butler Yeats - July 6 [1907]. July 1907. 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/9010p2njpg-cor.
APA, 6th edition
Gonne, Maud, 1866-1953. (July 1907)[Letter written by Maud Gonne to William Butler Yeats - July 6 [1907]]. 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/9010p2njpg-cor.
Chicago
Gonne, Maud, 1866-1953, Letter written by Maud Gonne to William Butler Yeats - July 6 [1907], July 1907, 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/9010p2njpg-cor.