1. Partial Differential Equations for Scientists and Engineers by Stanley Farlow

2. Applied Partial Differential Equations by Richard Haberman

http://math.umn.edu/~olver/pdn.html

4. Partial Differential Equations: An Introduction by Walter Strauss

http://www-users.math.umn.edu/~olver/pde.html

http://fac.ksu.edu.sa/eelmahdy/course-material/246077