MATHEMATICAL METHODS IN PHYSICAL SCI, BOAS. 2nd edition chapters 11, 12, 13, and 16
Textbook was Mary Boas, second edition. This seems to be the standard book for these type of course are most universities, at least the ones I know about. It is a good book, but more detailed examples would have been nice. So another book such as the problem solvers type books might be useful to have.