Wagnerian Heroines. A Century Of Great Isoldes and Brünnhildes 

Hello Ki.Liese. Re this book which you have been adding to multiple articles:
Liese, Kirsten, Wagnerian Heroines. A Century Of Great Isoldes and Brünnhildes, English translation: Charles Scribner, Edition Karo, Berlin, 2013

Please ensure that when adding this book to articles, you do not imply that it was used as a source. It needs to go in a separate section entitled Further reading  and that section must come after the References section not before it. Also, please indicate the relevant page numbers in the book for each singer to whose article you are adding the book. This page has guidelines on these types of additions, and this page has guidance if you have any connection to the author of the book. Best wishes,