APA aipamena

Krugman, P. (1991). Geography and trade. Leuven, Belgium: Leuven University Press.

Chicago Style aipamena

Krugman, Paul. Geography and Trade. Leuven, Belgium: Leuven University Press, 1991.

MLA aipamena

Krugman, Paul. Geography and Trade. Leuven, Belgium: Leuven University Press, 1991.

Kontuz: berrikusi erreferentzia hauek erabili aurretik.