@article{IM_1988__94_2_143638,
     author = {John W. Morgan},
     title = {Ergodic theory and free actions of groups on {IR-trees.}},
     journal = {Inventiones mathematicae},
     pages = {605--622},
     publisher = {mathdoc},
     volume = {94},
     number = {2},
     year = {1988},
     zbl = {0676.57001},
     url = {http://geodesic.mathdoc.fr/item/IM_1988__94_2_143638/}
}