APA (7th ed.) Citation

Harrigan, E., & Hart, T. (1887). Old Keen, the Secret Service detective. Tousey.

Chicago Style (17th ed.) Citation

Harrigan, Edward, and Tony Hart. Old Keen, the Secret Service Detective. New York: Tousey, 1887.

MLA (9th ed.) Citation

Harrigan, Edward, and Tony Hart. Old Keen, the Secret Service Detective. Tousey, 1887.

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