Lax P.D.: Phragmen-Lindelöf theorem in harmonic analysis and its application to some questions in the theory of elliptic equations
. Comm. Pure Appl. Math. 10 (1957), 361-389. MR 0093706
 Oleĭnik O.A., Josif'jan G.A.: The Saint Venant principle for a mixed problem of elasticity theory and its applications
. Dokl. Akad. Nauk USSR (5) 233 (1977), 824-827. MR 0668743
 Tarba L.A.: On behaviour of the solutions to the elliptic equations in unbounded domains (in Russian). VINITI (1980), 2573.
 Grishina T.V.: On the regularity and the behaviour of solutions to the nonlinear elliptic Dirichlet boundary value problem in the neighbourhood of the singular point of the boundary (in Russian). Vestnik Mosk. Un. ser. 1, Matematika, Mechanika (1986), 4 84-87.
 Kondratiev V.A., Landis V.M.: Qualitative theory of linear partial differential equations of second order (in Russian). VINITI, Itogi nauki i techn., Sovr. probl. mat., Fund. napravlenije 32 (1988), 99-215.
 Sitnik S.M.: Rate of decay of the solutions of some elliptic and ultraelliptic equations (in Russian)
. Differentsial'nye Uravneniya (3) 24 (1988), 538-539. MR 0941211
 Kantorovich L.V., Akilov C.P.: Functional Analysis (in Russian)
. Nauka, Moskva, 1977, second edition. MR 0511615