Franz Cumont, Lux Perpetua (Paris: Geuthner, 1949), pp. 142–188, idem, AfterLife in Roman Paganism (New York: Dover, 1959 [1922]), pp. 91–109, esp. pp. 96–106; M. P. Nilsson, Geschichte der griechischen Religion 2nd ed. (Munich: Beck, 1961), vol. 2, pp. 278–279.