@article{DAN_1969_187_4_a1,
     author = {B. M. Gurevich},
     title = {Topological entropy of a countable {Markov} chain},
     journal = {Doklady Akademii Nauk},
     pages = {715--718},
     publisher = {mathdoc},
     volume = {187},
     number = {4},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1969_187_4_a1/}
}