@article{SM_1991_70_2_a1,
     author = {G. G. Kazaryan and V. N. Markaryan},
     title = {Lower bounds for the~functional dimension of the solution space of hypoelliptic operators},
     journal = {Sbornik. Mathematics},
     pages = {341--353},
     publisher = {mathdoc},
     volume = {70},
     number = {2},
     year = {1991},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1991_70_2_a1/}
}