Gaya APA
API, . (1971).
API specification for pipeline valves (stel gate,plug,ball,and check valves) (1971).
Washington DC:
Washington : API,.
Gaya MLA
API, .
"API specification for pipeline valves (stel gate,plug,ball,and check valves)".
1971
Washington DC:
Washington : API,,
1971.
Text.