APA (7th ed.) Citation

Seward, W. H., Barton, W. E., & William E. Barton Collection of Lincolniana. (1864). Letter: Washington, D.C., to Charles Sumner, Boston.

Chicago Style (17th ed.) Citation

Seward, William H., William E. Barton, and William E. Barton Collection of Lincolniana. Letter: Washington, D.C., to Charles Sumner, Boston. 1864.

MLA (8th ed.) Citation

Seward, William H., et al. Letter: Washington, D.C., to Charles Sumner, Boston. 1864.