Hello Mark,
You might also check: John Graziano, Compositional Strategies in Popular Song Form of the Early Twentieth Century,” in A Music-Theoretical Matrix: Essays in Honor of Allen Forte (Part V), ed. David Carson Berry, Gamut 6/2 (2013): 95–131. It’s online.
As Graziano writes: “In this essay, I am interested in exploring the expansion of harmonic possibilities that took place in the release or bridge section of the chorus, with the adoption of the AABA form during the late 1910s and ’20s.”
–David