Zu Birkhoffs Lösung des Ergodenproblems

[1]  G. Birkhoff.  Proof of a Recurrence Theorem for Strongly Transitive Systems. , 1931, Proceedings of the National Academy of Sciences of the United States of America.

[2]  E. Hopf.  On the Time Average Theorem in Dynamics. , 1932, Proceedings of the National Academy of Sciences of the United States of America.