Hoffmann, R. (1946). Dunkler Engel. Paul List verlag.
Cita Chicago (17th ed.)Hoffmann, Ruth. Dunkler Engel. Leipzig: Paul List verlag, 1946.
Cita MLA (8th ed.)Hoffmann, Ruth. Dunkler Engel. Paul List verlag, 1946.
Atenció: Aquestes cites poden no estar 100% correctes.