Cumper,George E. (1991). The evaluation of national systems. Oxford University Press.
Chicago Style aipamenaCumper,George E. The Evaluation of National Systems. New york: Oxford University Press, 1991.
MLA aipamenaCumper,George E. The Evaluation of National Systems. Oxford University Press, 1991.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.