APA
American Petroleum Institute A., . (2017). Check valves: flanged, lug, wafer and butt-welding. Washington: American Petroleum Institute, API.
Chicago
American Petroleum Institute API, . 2017. Check valves: flanged, lug, wafer and butt-welding. Washington: American Petroleum Institute, API.
Harvard
American Petroleum Institute A., . (2017). Check valves: flanged, lug, wafer and butt-welding. Washington: American Petroleum Institute, API.
MLA
American Petroleum Institute API, . Check valves: flanged, lug, wafer and butt-welding. Washington: American Petroleum Institute, API. 2017.