@article{DAN_1973_212_4_a4,
     author = {M. I. Kanovitch},
     title = {Irreducibility of the languages of a step-by-step semantic system},
     journal = {Doklady Akademii Nauk},
     pages = {800--803},
     year = {1973},
     volume = {212},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_212_4_a4/}
}