APA (7th ed.) Citation

Courant, R. a. R. H. (1946). What is mathematics? Oxford University.

Chicago Style (17th ed.) Citation

Courant, Richard and Robbins Herbert. What Is Mathematics? Oxford University, 1946.

MLA (9th ed.) Citation

Courant, Richard and Robbins Herbert. What Is Mathematics? Oxford University, 1946.

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