APA

American Petroleum Institute A., . (1990). Bulletin on referenced standards for committee 6, standardization of valves and wellhead equipment. Washington: American Petroleum Institute, API.

Chicago

American Petroleum Institute API, . 1990. Bulletin on referenced standards for committee 6, standardization of valves and wellhead equipment. Washington: American Petroleum Institute, API.

Harvard

American Petroleum Institute A., . (1990). Bulletin on referenced standards for committee 6, standardization of valves and wellhead equipment. Washington: American Petroleum Institute, API.

MLA

American Petroleum Institute API, . Bulletin on referenced standards for committee 6, standardization of valves and wellhead equipment. Washington: American Petroleum Institute, API. 1990.