Looking for sheet music of the warm-up exercises we use? One of our members found it. It's here. We normally use Exercises 1 and 2. Yes, we also use "Ma, Meh, Me, Mo, Mu" which, with an "up a half" key change, is there as Exercise 4.
A good set of chords is also available here.
If you enjoy barbershop style music, watch for our next show and come hear us sing.