Não informado. (2017). The Petroleum Engineer. Petroleum Engineer Publishing.
Chicago-viite (17. p.)Não informado. The Petroleum Engineer. Dallas, Tex: Petroleum Engineer Publishing, 2017.
MLA-viite (8. p.)Não informado. The Petroleum Engineer. Petroleum Engineer Publishing, 2017.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.