Bethe entered the University of Munich in April 1926, where Sommerfeld took him on as a student on Meissner's recommendation. Sommerfeld taught an advanced course on differential equations in physics, which Bethe enjoyed. Because he was such a renowned scholar, Sommerfeld frequently received advance copies of scientific papers, which he put up for discussion at weekly evening seminars. When Bethe arrived, Sommerfeld had just received Erwin Schrödinger 's papers on wave mechanics.