Stockhausen was by now world famous. He toured the United States and many other countries with a small group of musicians performing modern music. His music was not only listened to by fans of classical music but was also becoming part of popular youth culture. His picture was included on the front cover of the Beatles’s record Sgt. Pepper's Lonely Hearts Club Band. The record company Deutsche Grammophon sold more copies of his music than of any other modern composer except Stravinsky.