MLA
Shelby, W. B. Telegram from Colonel W. B. Shelby to Brigadier General Daniel Ruggles - June 18, 1862. 1862. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 6, Folder 6. https://digital.library.emory.edu/purl/0343r228qr-cor.
APA, 6th edition
Shelby, W. B. (1862). Telegram from Colonel W. B. Shelby to Brigadier General Daniel Ruggles - June 18, 1862 (Box 6, Folder 6) [Telegrams]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0343r228qr-cor.
Chicago
Shelby, W. B. “Telegram from Colonel W. B. Shelby to Brigadier General Daniel Ruggles - June 18, 1862.” Telegrams. Civil War Collection, 1862. Box 6, Folder 6. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0343r228qr-cor.