Partial Differential Equations (Paperback, 4th ed. 1982. Softcover reprint of the original 4th ed. 1982)

This book is a very well-accepted introduction to the subject. In it, the author identifies the significant aspects of the theory and explores them with a limited amount of machinery from mathematical analysis. Now, in this fourth edition, the book has again been updated with an additional chapter on Lewy's example of a linear equation without solutions.