Não informado. (1973). International petroleum abstracts. Institute of Petroleum.
Chicago-viite (17. p.)Não informado. International Petroleum Abstracts. London: Institute of Petroleum, 1973.
MLA-viite (8. p.)Não informado. International Petroleum Abstracts. Institute of Petroleum, 1973.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.