@article{MOMA_1978__86_177876,
     author = {Ulrich Krengel},
     title = {On the {Speed} of {Convergence} in the {Ergodic} {Theorem.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {3--6},
     publisher = {mathdoc},
     volume = {86},
     year = {1978},
     zbl = {0352.28008},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1978__86_177876/}
}