Dyfyniad APA

Frederick, J. G. (1929). Selling by telephone. Business Bourse Publishers.

Dyfyniad Arddull Chicago

Frederick, J. George. Selling by Telephone. New York: Business Bourse Publishers, 1929.

Dyfyniad MLA

Frederick, J. George. Selling by Telephone. Business Bourse Publishers, 1929.

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