@article{MZM_1999_65_5_a14,
     author = {R. I. Grigorchuk},
     title = {Ergodic theorems for the actions of a~free group and a~free semigroup},
     journal = {Matemati\v{c}eskie zametki},
     pages = {779--783},
     publisher = {mathdoc},
     volume = {65},
     number = {5},
     year = {1999},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1999_65_5_a14/}
}