I just came across the name of Bart in the book 'Woody Guthrie. American radical'. Written by Will Kaufman and published in 2011. He is mentioned on page 85. Woody Guthrie mentioned his name in a letter to Marjorie Maza, when he wrote about a series of concerts for the Teachers Union. The Almanacs wanted to hire Leadbelly, Bart and others .... The exact date of the letter is not known, but should be between Septemberr and December 1942.