The Forgotten Trinity by James R. White
This is an excellent study of the Godhead. White deals with complex doctrinal issues in a readable and understandable manner. At the same time he does not sidestep the issues, but gives thorough and careful attention to the biblical texts. His exegesis of the pertinent passages is of special value and worth filing away for future examination. For those in need of a solid overview of the Trinity I recommend The Forgotten Trinity highly.