Independent Petroleum Association of America. The Oil producing industry in your state. Petroleum Independent Publishers.
Chicago-referens (17:e uppl.)Independent Petroleum Association of America. The Oil Producing Industry in Your State. [Washington: Petroleum Independent Publishers.
MLA-referens (8:e uppl.)Independent Petroleum Association of America. The Oil Producing Industry in Your State. Petroleum Independent Publishers.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.