APA (7th ed.) Citation

Courant, R., & Robbins, H. E. j. a. (1941). What is mathematicsn An elementary approach to ideas and methods. Oxford university press.

Chicago Style (17th ed.) Citation

Courant, Rchard, and Herbert Ellis joint author Robbins. What Is Mathematicsn An Elementary Approach to Ideas and Methods. London, New York: Oxford university press, 1941.

MLA (9th ed.) Citation

Courant, Rchard, and Herbert Ellis joint author Robbins. What Is Mathematicsn An Elementary Approach to Ideas and Methods. Oxford university press, 1941.