Ms. Mae's volume is very complete and accurate. It has turned into a great resource and in a short time has answered several questions for me regarding chords and, most importantly, choosing the right chord fingerings in order to assure smooth transitions between chords.
If you need to find a chord, this is the book. Although written for chromatic mountain dulcimer, works for diatonic too - just can't do all the chords in the book. Easy to find what you need, or chord variations of your hand can't reach a tune's suggested chord.