APA

Norman D. A., American Petroleum Institute A. & Norman D. A. (1984). Indefinite pricing provisions in natural gas contracts. Washington: American Petroleum Institute, API.

Chicago

Norman Donald A, American Petroleum Institute API and Norman Donald A. 1984. Indefinite pricing provisions in natural gas contracts. Washington: American Petroleum Institute, API.

Harvard

Norman D. A., American Petroleum Institute A. and Norman D. A. (1984). Indefinite pricing provisions in natural gas contracts. Washington: American Petroleum Institute, API.

MLA

Norman Donald A, American Petroleum Institute API and Norman Donald A. Indefinite pricing provisions in natural gas contracts. Washington: American Petroleum Institute, API. 1984.