Saaty, T. L., & Kainen, P. C. (1977). The four-colour problem: Assaults and conquest. McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)Saaty, Thomas L., agus Paul C. Kainen. The Four-colour Problem: Assaults and Conquest. Nueva York: McGraw-Hill, 1977.
Lua MLA (9ú heag.)Saaty, Thomas L., agus Paul C. Kainen. The Four-colour Problem: Assaults and Conquest. McGraw-Hill, 1977.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.