I have ordered this book in order to try and find out more information:
'Die Komponisten Eduard und Richard Franck - Leben und Werk, Dokumente, Quellen'
('The Composers Eduard and Richard Franck - Life and Work, Documents, Sources')
https://www.booklooker.de/app/detail.php?aktionID=34577198&setMediaType=0
'Die Komponisten Eduard und Richard Franck - Leben und Werk, Dokumente, Quellen'
('The Composers Eduard and Richard Franck - Life and Work, Documents, Sources')
https://www.booklooker.de/app/detail.php?aktionID=34577198&setMediaType=0