this volume is based on pde courses given by the authors at the courant Institute and at the University of Notre Dame, Indiana. Presented are basic methods for obtaining various a priori estimates for second order equations of Elliptic type with particular emphasis on maximal principles, harnack inequalities, and their applications. The equations considered in the book are linear; however, the presented methods also apply to nonlinear problems. this second edition has been thoroughly revised and in a new br>Chapter the authors discuss several methods for proving the existence of solutions of primarily the Dirichlet problem for various types of Elliptic equations.

[Source: Orient BlackSwan]