Não informado. European series. Political and Economic Planning.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. European Series. London: Political and Economic Planning.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. European Series. Political and Economic Planning.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.