APA (7th ed.) Citation

Lincoln, R. T., Barton, W. E., & William E. Barton Collection of Lincolniana. (1865). Letter: Chicago, to J[osiah] G[ilbert] Holland, n.p.

Chicago Style (17th ed.) Citation

Lincoln, Robert Todd, William E. Barton, and William E. Barton Collection of Lincolniana. Letter: Chicago, to J[osiah] G[ilbert] Holland, N.p. 1865.

MLA (8th ed.) Citation

Lincoln, Robert Todd, et al. Letter: Chicago, to J[osiah] G[ilbert] Holland, N.p. 1865.