APA (7th ed.) Citation

Posnack, E. R. (1946). The 21st century looks back. The William-Frederick press.

Chicago Style (17th ed.) Citation

Posnack, Emanuel Robert. The 21st Century Looks Back. New York: The William-Frederick press, 1946.

MLA (9th ed.) Citation

Posnack, Emanuel Robert. The 21st Century Looks Back. The William-Frederick press, 1946.