Lenore Thomson

An excellent book if you ever took the MBTI personality assessment and want to know what all those letters really stand for. Thomson looks at each personality type and analyzes it in a Jungian approach. Since this is a model and not a science, its accuracy is anyone's guess, but I did find my type analysis (INTJ) accurate and useful.

If you want in-depth analyses of the different type preferences, with Star Trek examples thrown in (ok, not just Star Trek), this is a great book.

This is an excellent handbook for understanding personality types. Easy enough for the lay and deep enough for the professional.