Nothing like a book, but just a good website for a free test and then a basic overview/description of what it all means. I had him take the test a few years back and he's an ENTJ. He's currently seeing a girl, and having a few issues with it and I suggested he look into MBTI, try to find out her type, etc. I don't really have any organized resources for him. I know the human metrics website test and then the little I have learned over the years is just from random websites and this forum (I really don't know all that much myself about MBTI). Though I know the basics of certain types that seem to have conflicts.