Saaty, T. L. (1986). The four color problem: Assaults and conquest. Dover Publications.
Dyfyniad Arddull ChicagoSaaty, Thomas L. The Four Color Problem: Assaults and Conquest. New York: Dover Publications, 1986.
Dyfyniad MLASaaty, Thomas L. The Four Color Problem: Assaults and Conquest. Dover Publications, 1986.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.