Petroleum Institute of the Philippines, Inc. (1971). Topics on the oil industry. s.n.
Citazione stile Chigago Style (17a edizione)Petroleum Institute of the Philippines, Inc. Topics on the Oil Industry. [Manila: s.n, 1971.
Citatione MLA (9a ed.)Petroleum Institute of the Philippines, Inc. Topics on the Oil Industry. s.n, 1971.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.