@article{DA_1980_20_a3,
     author = {A. V. Kozina},
     title = {A classification problem},
     journal = {Diskretnyj analiz i issledovanie operacij},
     pages = {41--48},
     year = {1980},
     number = {20},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DA_1980_20_a3/}
}