World petroleum directory: A yearly directory of the active operating oil companies of the world. R. Palmer.
Chicago Style (17th ed.) CitationWorld Petroleum Directory: A Yearly Directory of the Active Operating Oil Companies of the World. New York: R. Palmer.
MLA (9th ed.) CitationWorld Petroleum Directory: A Yearly Directory of the Active Operating Oil Companies of the World. R. Palmer.
Warning: These citations may not always be 100% accurate.