"Friedrich Adler". Laupheimer Museum, Museum of the History of Christians and Jews (in German). Retrieved 2021-02-09.
newspapers.com
"The German style of Jugendstil on exhibition at the Art Museum". Newspapers.com. The Philadelphia Inquirer from Philadelphia, Pennsylvania. September 25, 1988. p. 82 (6F). Retrieved 2021-02-09. several-small pieces of jewelry by Friedrich Adler (1878-1942), a Jew who died in Auschwitz is generally exemplary.