@article{VMUMM_1992_6_a1,
     author = {V. P. Serebryakov},
     title = {Conditions for the quasiregularity of a singular differential operator},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {7--9},
     year = {1992},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1992_6_a1/}
}