VARIATIONAL-PRINCIPLES FOR HYPOELLIPTIC EQUATIONS Статья FILIPPOV V.M. Doklady Akademii nauk SSSR. Mezhdunarodnaya Kniga, Moscow, Russian Federation. Том 285. 1985. С. 302-305
SPECTRAL PROPERTIES OF OPERATORS IN THE PROBLEM OF THE COMPRESSIBLE FLUID OSCILLATION IN ROTATING VESSELS Статья PAL P.K. Doklady Akademii nauk SSSR. Mezhdunarodnaya Kniga, Moscow, Russian Federation. Том 281. 1985. С. 529-534