Paul Knüpfer: 1865-1920 - Mozart, Wolfgang Amadeus and Weber, Carl Maria von and Wagner, Richard and Nicolai, Otto and Meyerbeer, Giacomo and Cornelius, Peter and Verdi, Giuseppe and Knüpfer, Paul and Jadlowker, Hermann ([Austro Mechana], 1980)
https://katalog.adlr.link/Record/0-1698702388