The most significant secondary literature would seem to be John Knox, Chapters in a Life of Paul (Nashville, TN: Abingdon, 1950); Philipp Vielhauer, “On the ‘Paulinism’ in Acts,” in Studies in Luke-Acts, ed. L.E. Keck and J.L. Martyn (Philadelphia: Fortress, 1980), pp. 33–50; and Gerd Ludemann, Paulus der Heidenapostel, 2 vols. (Göttingen: Vandenhoeck & Ruprecht, 1980–83), Vol. 1 has appeared in English as Gerd Luedemann, Paul, Apostle to the Gentiles, Studies in Chronology (Philadelphia: Fortress, 1984).