1. Bitsadze, A.V., Nekotorye klassy uravnenii v chastnykh
proizvodnykh (Some Classes of Partial Differential Equations), Moscow:
Nauka, 1981.
2. Smirnov, M.M., Vyrozhdayushchiesya giperbolicheskie
uravneniya (Degenerate Hyperbolic Equations), Minsk: Vysh.
Shk., 1997.
3. Soldatov, A.P., Odnomernye singulyarnye operatory i kraevye zadachi
teorii funktsii (One-Dimensional Singular Operators and Boundary Value Problems
of Function Theory), Moscow: Vyssh. Shk., 1991.
4. Rajabov, N.R., Vvedenie v teoriyu differentsial’nykh uravnenii v
chastnykh proizvodnykh so sverkhsingulyarnymi koeffitsientami (Introduction to the
Theory of Partial Differential Equations with Supersingular Coefficients),
Dushanbe, 1992.
5. Lomov, S.A. and Lomov, I.S., Osnovy matematicheskoi teorii
pogranichnogo sloya (Fundamentals of the Mathematical Theory of the Boundary
Layer), Moscow: Izd. Mosk. Univ., 2011.