Wagner, Richard: The Ring of the Niblung. Siegfried. The Twilight of the gods / Richard Wagner. Transl. by Margaret Armour. With illustr. by Arthur Rackham. London [u.a.] : Ballantyne & Co., 19XX : 2(19XX). London [u.a.] : Ballantyne & Co., 1911. Badische Landesbibliothek Karlsruhe, 100 B 80018 R, 2, https://nbn-resolving.org/urn:nbn:de:bsz:31-143475 / Public Domain Mark 1.0