Grossman, G. M., & Helpman, E. (2002). Interest groups and trade policy. Princeton University Press.
Chicago Style aipamenaGrossman, Gene M., and Elhanan Helpman. Interest Groups and Trade Policy. Princeton, N.J: Princeton University Press, 2002.
MLA aipamenaGrossman, Gene M., and Elhanan Helpman. Interest Groups and Trade Policy. Princeton University Press, 2002.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.