Hildegard Rütgers 1963. Between 1963 and 1965 she performed at the Salzburg Festival, the part of "Die Vertraute" (Her confidante) in a production of "Elektra" by Richard Strauss, conducted by Herbert von Karajan, alongside Astrid Varnay in the title role, and Martha Mödl, Hildegard Hillebrecht, James King and Eberhard Waechter in leading parts. The production of Mozart's "Die Zauberflöte" at the Salzburg Festival, with Rütgers as the Third Boy, was filmed and released as a made-for-television-movie in 1964. She appeared alongside Walter Kreppel as Sarastro, Roberta Peters as the Queen of the Night, Pilar Lorengar and Waldemar Kmentt as Pamina and Tamino,
Piano concertos by Wolfgang Amadeus Mozart it was probably J.C. Bach, whom Mozart admired, who introduced the structural innovation of allowing the keyboard to introduce new thematic material in its first entry. Concertos Nos 1–4 (K. 37, 39, 40 and 41) are orchestral and keyboard arrangements of sonata movements by other composers. The next three concertos (K. 107/1, 2 and 3), which are not numbered, are arrangements of piano sonatas by J.C. Bach (Op 5. Nos. 2, 3, and 4, all composed by 1766). Based on handwriting analysis of the autographs they are believed to date from 1771–72. Concerto No. 5, K. 175 from 1773 was