APA (7th ed.) Citation

Seward, W. H., Barton, W. E., & William E. Barton Collection of Lincolniana. (1862). Autograph letter signed: Washington, D.C., to John Hughes, [Paris?].

Chicago Style (17th ed.) Citation

Seward, William H., William E. Barton, and William E. Barton Collection of Lincolniana. Autograph Letter Signed: Washington, D.C., to John Hughes, [Paris?]. 1862.

MLA (8th ed.) Citation

Seward, William H., et al. Autograph Letter Signed: Washington, D.C., to John Hughes, [Paris?]. 1862.