Cita APA (7th ed.)

(2001). Portugal, Belgium. OECD Publications Services.

Cita Chicago (17th ed.)

Portugal, Belgium. Paris, France: OECD Publications Services, 2001.

Cita MLA (9th ed.)

Portugal, Belgium. OECD Publications Services, 2001.

Atenció: Aquestes cites poden no estar 100% correctes.