APA (7th ed.) Citation

Saaty, T. L., & Kainen, P. C. (1977). The four-colour problem: Assaults and conquest. McGraw-Hill.

Chicago Style (17th ed.) Citation

Saaty, Thomas L., and Paul C. Kainen. The Four-colour Problem: Assaults and Conquest. Nueva York: McGraw-Hill, 1977.

MLA (9th ed.) Citation

Saaty, Thomas L., and Paul C. Kainen. The Four-colour Problem: Assaults and Conquest. McGraw-Hill, 1977.