Levine, M. (1994). Effective problem solving (2nd edition.). Prentice-Hall of India.
Dyfyniad Arddull ChicagoLevine, Marvin. Effective Problem Solving. 2nd edition. Englewood Cliffs: Prentice-Hall of India, 1994.
Dyfyniad MLALevine, Marvin. Effective Problem Solving. 2nd edition. Prentice-Hall of India, 1994.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.