Complex sentence: Rev. Shoemaker wrote over thirty books, at least half of which were circulating before A.A. 's 12 Steps and Big Book were published in 1939 and being circulated in New York, Akron, and the Oxford Group.
Split into simpler sentences: Rev. Shoemaker wrote over thirty books, at least half of which were circulating before A.A. 's 12 Steps were first published in the Big Book in 1939. The book was circulated in New York, Akron, and the Oxford Group.