Courant, R., Robbins, H., & Stewart, I. (1996). What is mathematics?: An elementary approach to ideas and methods.-2nd ed (2nd ed.). Oxford University Press.

Courant, Richard, Herbert Robbins, and Ian Stewart. What Is Mathematics?: An Elementary Approach to Ideas and Methods.-2nd Ed. 2nd ed. New York: Oxford University Press, 1996.

Courant, Richard, et al. What Is Mathematics?: An Elementary Approach to Ideas and Methods.-2nd Ed. 2nd ed. Oxford University Press, 1996.