MLA
Engraving of "Robert E. Lee and His Generals," Published by John Smith, Philadelphia. John Smith, 1867. Stuart A. Rose Manuscript, Archives, and Rare Book Library, OP20. https://digital.library.emory.edu/purl/832r4xgzkt-cor.
APA, 6th edition
Engraving of "Robert E. Lee and His Generals," published by John Smith, Philadelphia (OP20). (1867). [Lithgraphs]. John Smith; Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/832r4xgzkt-cor.
Chicago
“Engraving of ‘Robert E. Lee and His Generals," Published by John Smith, Philadelphia.” Lithgraphs. Civil War Collection. Philadelphia, PA: John Smith, 1867. OP20. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/832r4xgzkt-cor.