@article{DAN_1975_221_6_a9,
     author = {B. I. Plotkin and C. E. Dididze and E. M. Kublanova},
     title = {On varieties of automata},
     journal = {Doklady Akademii Nauk},
     pages = {1284--1287},
     year = {1975},
     volume = {221},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1975_221_6_a9/}
}