Differential Equations with Boundary Value Problems - http://www.math.armstrong.edu/faculty/hollis/dewbvp By S. Hollis (Prentice Hall, 2002). Overview of contents, errata, software and link to purchasing page.
Status Code: 301 - Location: http://www.math.armstrong.edu/faculty/hollis/dewbvp/
Green's Functions - http://www.math.armstrong.edu/faculty/hollis/dewbvp Lecture notes introducing this technique for solving first and second order differential equations. Scanned (GIF) by Joceline Lega.
Pseudo-Differential Operators - http://www.math.armstrong.edu/faculty/hollis/dewbvp These lecture notes cover a first year graduate course that was given on pseudo-differential operators. The calculus on manifolds is developed and applied to prove propagation of singularities and the Hodge decomposition theorem.
Vibrating Drumhead - http://www.math.armstrong.edu/faculty/hollis/dewbvp A set of Mathematica packages which outline solutions of the wave equation in various coordinates.