Book of Deuteronomy have given various answers to the problem. The Deuteronomistic history theory is currently the most popular (Deuteronomy was originally just the law code and covenant, written to cement the religious reforms of Josiah, and later expanded to stand as the introduction to the full history); but there is an older theory which sees Deuteronomy as belonging to Numbers, and Joshua as a sort of supplement to it. This idea still has supporters, but the mainstream understanding is that Deuteronomy, after becoming the introduction to the history, was later detached from it and included with Genesis-Exodus-Leviticus-Numbers because it already had Moses
Leviticus Rabbah composed largely of older works. Its redactor made use of Genesis Rabbah, Pesikta de-Rav Kahana, and the Jerusalem Talmud, in addition to other ancient sources. The redactor appears to have referred also to the Babylonian Talmud, using several expressions in the sense in which only that work employs them. Leviticus Rabbah is not a continuous, explanatory interpretation to Leviticus, but a collection of exclusive sermons or lectures on the themes or texts of that book. It consists altogether of 37 such homilies, each of which constitutes a separate chapter. Leviticus Rabbah often refers to Scriptural passages on which the homilies