APA (7th ed.) Citation

Guy, R. K. (1981). Unsolved problems in number theory. Springer.

Chicago Style (17th ed.) Citation

Guy, Richard K. Unsolved Problems in Number Theory. New York [u.a.]: Springer, 1981.

MLA (9th ed.) Citation

Guy, Richard K. Unsolved Problems in Number Theory. Springer, 1981.

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