MLA
Miller, H. Prentice (Henry Prentice), 1905-1985. Letter from Henry Prentice Miller, Dean of Alumni at Emory University, to "Mrs. Clarence Blount" thanking her for donating several letters and a Emory Unit key to Emory University - June 6, 1976. June 6, 1976. Emory Unit Collection. Robert W. Woodruff Health Sciences Center. Library. https://digital.library.emory.edu/purl/303qv9s5xv-cor.
APA, 6th edition
Miller, H. Prentice (Henry Prentice), 1905-1985. (June 6, 1976)[Letter from Henry Prentice Miller, Dean of Alumni at Emory University, to "Mrs. Clarence Blount" thanking her for donating several letters and a Emory Unit key to Emory University - June 6, 1976]. Emory Unit Collection, Robert W. Woodruff Health Sciences Center. Library. https://digital.library.emory.edu/purl/303qv9s5xv-cor.
Chicago
Miller, H. Prentice (Henry Prentice), 1905-1985, Letter from Henry Prentice Miller, Dean of Alumni at Emory University, to "Mrs. Clarence Blount" thanking her for donating several letters and a Emory Unit key to Emory University - June 6, 1976, June 6, 1976, Emory Unit Collection, Robert W. Woodruff Health Sciences Center. Library. https://digital.library.emory.edu/purl/303qv9s5xv-cor.