APA (7th ed.) Citation

Chopin, F., Voynich, E. L., & Opieński, H. (1931). Chopin's letters. A.A. Knopf.

Chicago Style (17th ed.) Citation

Chopin, Frédéric, E. L. Voynich, and Henryk Opieński. Chopin's Letters. New York: A.A. Knopf, 1931.

MLA (9th ed.) Citation

Chopin, Frédéric, et al. Chopin's Letters. A.A. Knopf, 1931.