Drucker, P. F. (1999). Management challenges for the 21st century. Butterworth-Heinemann.
Dyfyniad Arddull ChicagoDrucker, Peter F. Management Challenges for the 21st Century. Oxford: Butterworth-Heinemann, 1999.
Dyfyniad MLADrucker, Peter F. Management Challenges for the 21st Century. Butterworth-Heinemann, 1999.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.