@article{INTF_1985_2_a4,
     author = {A. M. Vershik and I. P. Kornfeld},
     title = {General ergodic theory of transformation groups with invariant measure. {Chapter~4.} {Periodic} approximations and their applications. {Ergodic} theorems, spectral and entropy theory for general group actions},
     journal = {Itogi Nauki i Tekhniki. Seriya Sovremennye Problemy Matematiki. Fundamental'nye Napravleniya},
     pages = {70--89},
     year = {1985},
     volume = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/INTF_1985_2_a4/}
}