Drucker, P. (2006). Management challenges for the 21st Century. Palgrave Macmillan Punl.
Lua i Stíl Chicago (17ú heag.)Drucker, Peter. Management Challenges for the 21st Century. New York: Palgrave Macmillan Punl, 2006.
Lua MLA (9ú heag.)Drucker, Peter. Management Challenges for the 21st Century. Palgrave Macmillan Punl, 2006.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.