German soprano Elisabeth Schwarzkopf died Thursday at age 90. Along with Maria Callas, she was considered one of the greatest opera singers of the 20th century. Washington Post critic Tim Page and Schwarzkopf biographer Alan Jefferson comment on her career, which was not without controversy. And, from one of her many recordings, Schwarzkopf sings music by Richard Strauss: the song called "Dedication." George Szell leads the Berlin Radio Symphony Orchestra.