sentences:  In many instances, however, the sources are given in an inconvenient place or are entirely eliminated, while some references are even indicated by a later redactor, as, for example, Job 921, where mention of the source (Exodus Rabbah) is a later addition, the original redactor being unacquainted with Exodus Rabbah.The sources embrace not only the major portion of halakhic and aggadic literature during the ancient and geonic epochs, but also the aggadic literature as late as the 12th century.The author made use of the older midrashic works, such as Seder 'Olam, Sifra, Sifre, Sifre Zuṭa, Mekilta, the Baraita on the Thirty-two Middot, the Baraita on the Forty-nine Middot, and the Baraita on the Erection of the Tabernacle ("Meleket ha-Mishkan"), and he availed himself also of the Mishnah, both Talmudim, and Semaḥot, Kallah, and Soferim.