APA (7th ed.) Citation

Petrow, R., Petrow, R., & Petrow, R. (1974). The bitter years: The invasion and occupation of Denmark and Norway, April 1940-May 1945. Morrow.

Chicago Style (17th ed.) Citation

Petrow, Richard, Richard Petrow, and Richard Petrow. The Bitter Years: The Invasion and Occupation of Denmark and Norway, April 1940-May 1945. New York: Morrow, 1974.

MLA (8th ed.) Citation

Petrow, Richard, et al. The Bitter Years: The Invasion and Occupation of Denmark and Norway, April 1940-May 1945. Morrow, 1974.