@article{ZNSL_1976_59_a1,
     author = {I. L. Vulis},
     title = {Spectral asymptotics of elliptic strongly degenerate operators of arbitrary order},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {25--30},
     publisher = {mathdoc},
     volume = {59},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1976_59_a1/}
}