Trinitarianism in Second Temple Judaism

I’m currently reading Alan Segal’s Two Powers in Heaven in which he argues that certain strains of Jewish theology during the Second Temple and Rabbinic periods believed in multiple divine figures — divine hypostases — which was perceived by some as violating the standard of traditional monotheism. Next semester I hope to do my final research project on the development of Trinitarian thinking during this time, indicating that it was not at all a uniquely Christian invention, but had its roots in a variety of Judaic traditions, such as Philo’s Logos doctrine, second God, and divine triad. Michael Heiser has a nice, small article with a couple good links that I’m quite pleased to have found.