MLA
Castleman, Alfred L. (Alfred Lewis), 1809-1877. The Army of the Potomac : behind the scenes : a diary of unwritten history : from the organization of the Army, by General George B. McClellan, to the close of the campaign in Virginia, about the first day of January, 1863. 1863. Regimental Histories. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/713905qkxs-cor.
APA, 6th edition
Castleman, Alfred L. (Alfred Lewis), 1809-1877. (1863)[The Army of the Potomac : behind the scenes : a diary of unwritten history : from the organization of the Army, by General George B. McClellan, to the close of the campaign in Virginia, about the first day of January, 1863]. Regimental Histories, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/713905qkxs-cor.
Chicago
Castleman, Alfred L. (Alfred Lewis), 1809-1877, The Army of the Potomac : behind the scenes : a diary of unwritten history : from the organization of the Army, by General George B. McClellan, to the close of the campaign in Virginia, about the first day of January, 1863, 1863, Regimental Histories, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/713905qkxs-cor.