Lin taught a course at the Courant Institute, New York University, in 1992, and in 1995 Han used and augmented the notes for a course at the University of Notre Dame. They present some basic methods for obtaining various a priori estimates for second-order partial differential equations of the elliptic type, with a particular emphasis on maximal principles, Harnack inequalities, and their applications. Students should have some knowledge of real variables and Sobolev functions. No date is cited for the first edition, but to this second has been added a final chapter on the existence of solutions, primarily the Dirichlet problem for various types of elliptic equations. There is no index. Annotation ©2011 Book News, Inc., Portland, OR (booknews.com)