International organization and administration — European Economic Community — Treaty of Rome, 1957 (Article 37) — State trading monopolies and analogous schemes — French import licensing system for petroleum products — Regulations regarding distribution and service stations — Whether in conformity with Treaty of Rome — Court of Justice of the European Communities — Competence to give preliminary ruling — Obligation of domestic courts to refer issues to European Court of Justice (Article 177) — When applicable — The law of France.