APA (7th ed.) Citation

Wagner, R., & Solti, G. (1995). An introduction to Der Ring des Nibelungen. London.

Chicago Style (17th ed.) Citation

Wagner, Richard, and Georg Solti. An Introduction to Der Ring Des Nibelungen. London, England: London, 1995.

MLA (9th ed.) Citation

Wagner, Richard, and Georg Solti. An Introduction to Der Ring Des Nibelungen. London, 1995.