See Mary Boyce, Zoroastrians: Their Religious Beliefs and Practices (London: Routledge & Kegan Paul, 1979), pp. 101–144. On the religious foundation of Sassanian law and social institutions, see A. Perikhanian, “Iranian Society and Law,” in Ehsan Yarshater, ed., The Cambridge History of Iran (Cambridge: Cambridge Univ. Press, 1983), v. 3(2), pp. 627–680.