APA aipamena

Posnack, E. R. (1946). The 21st centrury looks back. New York: William-Frederick Press.

Chicago Style aipamena

Posnack, Emanuel R. The 21st Centrury Looks Back. New York: William-Frederick Press, 1946.

MLA aipamena

Posnack, Emanuel R. The 21st Centrury Looks Back. New York: William-Frederick Press, 1946.

Kontuz: berrikusi erreferentzia hauek erabili aurretik.