Sigfrid Fritzlar. (author of this entry); "Gabriele Baumgartner (compiler-editor); Dieter Hebig (compiler-editor) (24 May 2012). Neumann, Anni. Walter de Gruyter. p. 594. ISBN978-3-11-169913-4. Retrieved 27 November 2019. {{cite book}}: |author1= has generic name (help); |work= ignored (help)