APA (7th ed.) Citation

Ruoff, H. W. The Circle of Knowledge: A Classified, Simplified, Visualized Book of Answers.

Chicago Style (17th ed.) Citation

Ruoff, Henry W. The Circle of Knowledge: A Classified, Simplified, Visualized Book of Answers.

MLA (9th ed.) Citation

Ruoff, Henry W. The Circle of Knowledge: A Classified, Simplified, Visualized Book of Answers.

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