APA (7th ed.) Citation

Twain, M., & Branch, E. M. (1988). Mark Twain's letters. Univ. of California Pr.

Chicago Style (17th ed.) Citation

Twain, Mark, and Edgar M. Branch. Mark Twain's Letters. Berkeley, Calif. <<[u.a.]>>: Univ. of California Pr, 1988.

MLA (9th ed.) Citation

Twain, Mark, and Edgar M. Branch. Mark Twain's Letters. Univ. of California Pr, 1988.