1. Braunstein N. A. Le desir de Scarpia. Analytica, vol. 46, Paris, Navarin, 1986.
2. Cooke D. I Saw the World End, Oxford, Oxford University Press, 1979.
3. Cord W. O. An Introduction to Richard Wagner’s “Der Ring des Nibelungen”, Athens, Ohio University Press, 1983.
4. Donington R. Wagner’s “Ring” and Its Symbols, London, Faber and Faber, 1990.
5. Gutman R. Richard Wagner, New York, Harcourt Brace Jovanovich, 1990.