I don't know if this link will work, but I did find one copy of the Mitchell Trio Songbook through www.bookfinder.com. You could give it a click and see if you're interested. Mind you, this is from the "Mitchell Trio" days, after Chad left. I can type up the list of songs if you'd like. I paid $1.50 for my copy (way back in 1999), so I can't complain too much about it. Most likely, Barbara's book will be better for you.
-Joe Offer-