APA

Portal G., European Petroleum Industry Association, World Petroleum Congress (14th : 1994 : Stavanger) & European Petroleum Industry Association.Environmental legislation. : .

Chicago

Portal G.M.A, European Petroleum Industry Association, World Petroleum Congress (14th : 1994 : Stavanger) and European Petroleum Industry Association.Environmental legislation. : .

Harvard

Portal G., European Petroleum Industry Association, World Petroleum Congress (14th : 1994 : Stavanger) and European Petroleum Industry Association.Environmental legislation. : .

MLA

Portal G.M.A, European Petroleum Industry Association, World Petroleum Congress (14th : 1994 : Stavanger) and European Petroleum Industry Association.: . .