Gorbachuk V.I., Gorbachuk M.L. Boundary Value Problems for Operator Differential Equations

Kluwer, 1991. — 360 p. — ISBN: 9780792303817, 0792303814.The book deals with the theory of boundary value problems for second-order operator differential equations. The book provides a number of examples which prove that the operator approach makes it possible not only to extend the class of already studied partial differential equations and their boundary value problems, but also to look from another point of view to the spectral theory of self-adjoint boundary value problems for such classical expressions as those of Laplace and D'Alembert. We will not always formulate the results in the most general form. We have
preferred to select a somewhat average level of generality (a "golden mean"). The rest is added by way of comments and references.
To make reading easy, the principal statements are distinguished in the form of theorems, lemmas, corollaries, and remarks as well as formulas.