APA (7th ed.) Citation

Campbell, T., & Butler-Gunsaulus Collection. Autograph letter signed: To Dr. Cumming.

Chicago Style (17th ed.) Citation

Campbell, Thomas, and Butler-Gunsaulus Collection. Autograph Letter Signed: To Dr. Cumming.

MLA (8th ed.) Citation

Campbell, Thomas, and Butler-Gunsaulus Collection. Autograph Letter Signed: To Dr. Cumming.

Warning: These citations may not always be 100% accurate.