Drucker, P. F. (1957). America's next twenty years. New York: Happer and Brother.
Trích dẫn kiểu ChicagoDrucker, Peter F. America's Next Twenty Years. New York: Happer and Brother, 1957.
Deismireacht MLADrucker, Peter F. America's Next Twenty Years. New York: Happer and Brother, 1957.
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