I am looking to replace the book I am using in a mathematical methods in physics course I am teaching. We currently use a more mathematical book in Swedish and it is missing some content which we would like to include. I had my eyes on the mathematical methods book by Mary Boas but it is kind of brief (hardly even mentions in the 3rd edition) on the Green's function side. A work-around would of course be to hand out extra lecture notes on the subject, but it is something I would prefer not to do. Does anyone know of a good alternative with more or less the same level, but including more content on Green's functions (solutions for the Poisson equation in 2 and 3D, mirroring techniques, etc)?