MLA
Gonne, Maud, 1866-1953. Letter written by Maud Gonne to William Butler Yeats - [December 12 1900]. circa December 12, 1900. 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/6451g1k01k-cor.
APA, 6th edition
Gonne, Maud, 1866-1953. (circa December 12, 1900)[Letter written by Maud Gonne to William Butler Yeats - [December 12 1900]]. 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/6451g1k01k-cor.
Chicago
Gonne, Maud, 1866-1953, Letter written by Maud Gonne to William Butler Yeats - [December 12 1900], circa December 12, 1900, 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/6451g1k01k-cor.