APA (7th ed.) Citation

Rank, S. (2020). History's 9 most insane rulers. Regnery History.

Chicago Style (17th ed.) Citation

Rank, Scott. History's 9 Most Insane Rulers. Washington, D.C.: Regnery History, 2020.

MLA (9th ed.) Citation

Rank, Scott. History's 9 Most Insane Rulers. Regnery History, 2020.