APA (7th ed.) Citation

Spengler, O., & Helps, A. (1966). Letters, 1913-1936 ([1st American ed.].). Knopf.

Chicago Style (17th ed.) Citation

Spengler, Oswald, and Arthur Helps. Letters, 1913-1936. [1st American ed.]. New York: Knopf, 1966.

MLA (9th ed.) Citation

Spengler, Oswald, and Arthur Helps. Letters, 1913-1936. [1st American ed.]. Knopf, 1966.