President of the Austrian Parliament Barbara Prammer speaks prior to the premiere of the opera “Spiegelgrund,” which depicts atrocities perpetrated by Nazis on children in a Vienna hospital during the Holocaust. It was performed at the Austrian Parliament in Vienna on Jan. 25. “Spiegelgrund” is the work of Austrian composer Peter Androsch, whose great grandfather died in a concentration camp. (DIETER NAGL/AFP/Getty Images)

Robert Holzer (back) and Karl M. Sibelius (front) in a scene from “Spiegelgrund." Nazis had a campaign to methodically kill mentally or physically deficient children during World War II. (DIETER NAGL/AFP/Getty Images)

Katerina Beranova (L) and Alexandra Diesterhoeft (R) perform during the premiere of the opera “Spiegelgrund." Spiegelgrund was the name of a clinic for socially deprived children. These “anti-social” or “problem” children failed to measure up to the norm in Vienna during the Nazi dictatorship and were collected for extermination without their parents’ or caretakers’ knowledge or consent. (DIETER NAGL/AFP/Getty Images