APA (7th ed.) Citation

Aiken, H. D. (1956). The Age of ideology: The 19th century philosophers ([9th printing].). New American Library.

Chicago Style (17th ed.) Citation

Aiken, Henry D. The Age of Ideology: The 19th Century Philosophers. [9th printing]. New York [etc.]: New American Library, 1956.

MLA (9th ed.) Citation

Aiken, Henry D. The Age of Ideology: The 19th Century Philosophers. [9th printing]. New American Library, 1956.