http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
How to understand Wagner's Ring of the Nibelung
the story and descriptive analysis with musical examples of the leading motives of each drama
by Gustav Kobbe ; together with a sketch of Wagner's life by N. Kilburn.
"The Rhinegold (Das Rheingold), The Valkyr ( Die Walkure), Siegfried (Siegfried), The dusk of the gods (Gotterdammerung)"
Reprint of the 1916 edition published by W. Reeves, London.