O. A. Oleĭnik
Matematicheskie metody v teorii pogranichnogo sloi͡a
Different︠s︡ialʹnye uravnenii︠a︡ i ikh prilozhenii︠a︡
Lekt︠s︡ii ob uravnenii︠a︡kh s chastnymi proizvodnymi
Matematicheskie metody mekhaniki deformiruemogo tverdogo tela
Matematicheskie zadachi teorii silʹno neodnorodnykh uprugikh sred
Second order equations with nonnegative characteristic form
Second order equations with nonnegative characteristic form [by] O.A. Oleǐnik and E.V. Radkevič
Second Order Equations with Nonnegative Form