In graduate physics I used Jackson, Griffiths and Eyges as references and each of them bring something valuable to the table in terms of their approach, examples and derivations. This book was refreshing in that it takes the time to expand on the fundamental idea of mathematical fields and the potentials that lead to them. There is great coverage of Newtonian potentials, Green's functions, method of images and other classic concepts that figure into the inverse square fields common in physics. This is a great reference to add to your collection if you're interested in the subject.