APA (7th ed.) Citation

Harding, B. (1941). Imperial twilight: The story of Karl and Zita of Hungary. Blue Ribbon Books.

Chicago Style (17th ed.) Citation

Harding, Bertita. Imperial Twilight: The Story of Karl and Zita of Hungary. Garden City, N.Y.: Blue Ribbon Books, 1941.

MLA (9th ed.) Citation

Harding, Bertita. Imperial Twilight: The Story of Karl and Zita of Hungary. Blue Ribbon Books, 1941.