Não informado. (1970). Working paper series. National Bureau of Economic Research.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Working Paper Series. Cambridge, Mass: National Bureau of Economic Research, 1970.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Working Paper Series. National Bureau of Economic Research, 1970.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.