My choice would be **Boundary Value Problems and Green's Functions** by Ivar Stakgold. It have an introduction to *distribution theory* and them apply it to finding Green's functions. It includes: - ODE - PDE with initial conditions - PDE with boundary conditions. I found a preview [here](http://cam.ucsd.edu/~mholst/pubs/dist/StHo2011a-preview.pdf) Cheers