an Entity references as follows:
Erwin Schück (1879 – 1919), better known by his stage name Erwin Sembach, was an opera singer with the Vienna Volksoper during its earliest years of producing operas, immediately before and during World War I. His greatest roles there were Masetto in Mozart's Don Giovanni, Papageno in Mozart's The Magic Flute, and Krušina in Smetana's The Bartered Bride. (There was a successful German opera singer using the stage name Johannes Sembach during this same period, which may lead to some confusion when newspaper articles simply refer to the singer as "Herr Sembach".)