@article{10_4064_cm101_2_11,
     author = {Roland Zweim\"uller},
     title = {Hopf's ratio ergodic theorem by inducing},
     journal = {Colloquium Mathematicum},
     pages = {289--292},
     publisher = {mathdoc},
     volume = {101},
     number = {2},
     year = {2004},
     doi = {10.4064/cm101-2-11},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm101-2-11/}
}