APA (7th ed.) Citation

Heitmann, West, & Bungert. (2003). Secret intelligence in the twentieth century. Frank Cass.

Chicago Style (17th ed.) Citation

Heitmann, West, and Bungert. Secret Intelligence in the Twentieth Century. London: Frank Cass, 2003.

MLA (8th ed.) Citation

Heitmann, et al. Secret Intelligence in the Twentieth Century. Frank Cass, 2003.