@article{MZM_2002_71_4_a8,
     author = {Nguyen Minh Tri},
     title = {Some {Examples} of {Nonhypoelliptic} {Infinitely} {Degenerate} {Elliptic} {Differential} {Operators}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {567--580},
     publisher = {mathdoc},
     volume = {71},
     number = {4},
     year = {2002},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2002_71_4_a8/}
}