APA (7th ed.) Citation

Lincoln, M. T., Barton, W. E., & William E. Barton Collection of Lincolniana. (1865). Autograph letter signed: Washington, D.C., to [Queen Victoria, London].

Chicago Style (17th ed.) Citation

Lincoln, Mary Todd, William E. Barton, and William E. Barton Collection of Lincolniana. Autograph Letter Signed: Washington, D.C., to [Queen Victoria, London]. 1865.

MLA (8th ed.) Citation

Lincoln, Mary Todd, et al. Autograph Letter Signed: Washington, D.C., to [Queen Victoria, London]. 1865.