APA (7th ed.) Citation

Nagell, T. (1964). Introduction to number theory (2. ed.). Chelsea.

Chicago Style (17th ed.) Citation

Nagell, Trygve. Introduction to Number Theory. 2. ed. New York: Chelsea, 1964.

MLA (9th ed.) Citation

Nagell, Trygve. Introduction to Number Theory. 2. ed. Chelsea, 1964.