Here's a start for you, Jack: Pete's Forehead: a remembrance of Pete Seeger By Joanna Cazden January 21, 2015

"...Pete didn't look at me, focusing on an alto recorder, then a tenor, then back to the alto. "What key are you in?" he asked. "E-minor," I said, playing the accompinament that had fit my voice for years. He repeated the question several times until I realized that he was just being polite. He knew what key he wanted and would persist until we landed there!..."