Cita APA (7th ed.)

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

Cita Chicago (17th ed.)

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

Cita MLA (9th ed.)

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