@article{DAN_1982_267_4_a10, author = {G. G. Ponomarenko}, title = {On $r$-indistinguishability of finite automata}, journal = {Doklady Akademii Nauk}, pages = {806--807}, publisher = {mathdoc}, volume = {267}, number = {4}, year = {1982}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1982_267_4_a10/} }