I want to buy another Partial differential equation and Boundary value problems textbook.
The ones I have are:
1) Partial Differential Equation, An Introduction by Walter A. Strauss.
2) Partial differential equation and Boundary value problems by Nakhle Asmar.
3) Differential Equation with Boundary Value Problems by Dennis G. Zill and Michael R. Cullen.
4) Boundary value problems and Partial differential equations by David L. Powers.
5) Elementary Differential Equation and Boundary Value Problems by William E. Boyce and Richard C. Diprima.
Each book really have different presentation. Since I study on my own, I have to look at different point of views. I like 2) and 3) the best. The others are not very good.