@article{DA_1999_6_2_a4,
     author = {R. M. Larin and M. Yu. Kalugina},
     title = {A~problem of constructing a~hierarchical structure},
     journal = {Diskretnyj analiz i issledovanie operacij},
     pages = {42--47},
     publisher = {mathdoc},
     volume = {6},
     number = {2},
     year = {1999},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DA_1999_6_2_a4/}
}