@article{IM2_1974_8_6_a2,
     author = {V. M. Levchuk},
     title = {Subgroups of the unitriangular group},
     journal = {Izvestiya. Mathematics},
     pages = {1191--1208},
     year = {1974},
     volume = {8},
     number = {6},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1974_8_6_a2/}
}