MLA
Yeats, W. B. (William Butler), 1865-1939. Easter, 1916. 1916. Stuart A. Rose Manuscripts, Archives, and Rare Books Library Digitized Books Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/733rv15fb2-cor.
APA, 6th edition
Yeats, W. B. (William Butler), 1865-1939. (1916)[Easter, 1916]. Stuart A. Rose Manuscripts, Archives, and Rare Books Library Digitized Books Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/733rv15fb2-cor.
Chicago
Yeats, W. B. (William Butler), 1865-1939, Easter, 1916, 1916, Stuart A. Rose Manuscripts, Archives, and Rare Books Library Digitized Books Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/733rv15fb2-cor.