Posnack, E. R. (1946). The 21st centrury looks back. New York: William-Frederick Press.
Παραπομπή Chicago StylePosnack, Emanuel R. The 21st Centrury Looks Back. New York: William-Frederick Press, 1946.
Deismireacht MLAPosnack, Emanuel R. The 21st Centrury Looks Back. New York: William-Frederick Press, 1946.
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