APA Edition Citation

Hacker, L. M., & Zahler, H. S. (1952). Unitd States in the 20th century.

Chicago Edition Citation

Hacker, Louis M., and Helene S. Zahler. Unitd States in the 20th Century. 1952.

MLA Edition Citation

Hacker, Louis M., and Helene S. Zahler. Unitd States in the 20th Century. 1952.

Warning: These citations may not always be 100% accurate.