United Nations Economic Commission for Europe. (1979). The Gas Situation in the ECE Region Around the Year 1990. ELSEVIER.
Cita Chicago (17th ed.)United Nations Economic Commission for Europe. The Gas Situation in the ECE Region Around the Year 1990. ELSEVIER, 1979.
Cita MLA (8th ed.)United Nations Economic Commission for Europe. The Gas Situation in the ECE Region Around the Year 1990. ELSEVIER, 1979.
Atenció: Aquestes cites poden no estar 100% correctes.