Dyfyniad APA

American Telephone and Telegraph Company. (1979). The bell journal of economics. American Telephone and Telegraph Company.

Dyfyniad Arddull Chicago

American Telephone and Telegraph Company. The Bell Journal of Economics. Lancaster: American Telephone and Telegraph Company, 1979.

Dyfyniad MLA

American Telephone and Telegraph Company. The Bell Journal of Economics. American Telephone and Telegraph Company, 1979.

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