MLA
Groganphoto (Danville, Ill.). Chas. Maxwell, Guard, Lincoln's tomb, Springfield, Ill.. unknown. Robert Langmuir African American Photograph Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3418kprr8j-cor.
APA, 6th edition
Groganphoto (Danville, Ill.). (unknown)[Chas. Maxwell, Guard, Lincoln's tomb, Springfield, Ill.]. Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3418kprr8j-cor.
Chicago
Groganphoto (Danville, Ill.), Chas. Maxwell, Guard, Lincoln's tomb, Springfield, Ill., unknown, Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3418kprr8j-cor.