最後の警告
Conrich, Ian (2004). “Before Sound: Universal, Silent Cinema, and the Last of the Horror-Spectaculars”. In Price, Stephen. The Horror Film. Rutgers, New Jersey: Rutgers University Press. pp. 40–57. ISBN 978-0-813-53363-6
Maltin, Leonard; Green, Spencer; Edelman, Rob (2010). Leonard Maltin's Classic Movie Guide. New York: Plume. ISBN 978-0-452-29577-3. https://books.google.com/books?id=hLtaAAAAYAAJ
McCaffrey, Donald (1999). Guide to the Silent Years of American Cinema. Reference Guides to the World's Cinema. Santa Barbara, California: Greenwood Publishing Group.