to refute Graetz and Jellinek, but after years of research contended in 1941 that de León himself was the most likely author. Scholem noted the Zohar's frequent errors in Aramaic grammar, its suspicious traces of Arabic and Spanish words and sentence patterns, and its lack of knowledge of the land of Israel. Scholem views the author as having based the Zohar on a wide variety of pre-existing Jewish sources, while at the same time inventing a number of fictitious works that the Zohar supposedly quotes, e.g., the Sifra de-Adam, the Sifra de-Hanokh, the Sifra di-Shelomo Malka, the Sifra de-Rav Hamnuna Sava, the Sifra de-Rav Yeiva Sava, the Sifra de-Aggadeta, the Raza de-Razin and many others. Scholem's views are widely held as accurate among historians of the Kabbalah, but they are not uncritically accepted. Scholars who continue to research the background of the Zohar include Yehuda Liebes (who wrote his doctorate thesis for Scholem on the subject, Dictionary of the Vocabulary of the Zohar in 1976), and Daniel C. Matt, also a student of Scholem's who has reconstructed a critical edition of the Zohar based on manuscripts. Academic studies of the Zohar show that many of its ideas are based in the Talmud, various works of midrash, and earlier Jewish mystical works. Scholem writes: The writer had expert knowledge of the early material and he often used it as a foundation for his expositions, putting into it variations of his own. His main sources were the Babylonian Talmud, the complete Midrash Rabbah, the Midrash Tanhuma, and the two Pesiktot (Pesikta De-Rav Kahana or Pesikta Rabbati), the Midrash on Psalms, the Pirkei de-Rabbi Eliezer, and the Targum Onkelos. Generally speaking, they are not quoted exactly, but translated into the peculiar style of the Zohar and summarized. [...] Less use is made of the halakhic Midrashim, the Jerusalem Talmud, and the other Targums, nor of the Midrashim like the Aggadat Shir ha-Shirim, the Midrash on Proverbs, and the Alfabet de-R. Akiva. It is not clear whether the author used the Yalkut Simeoni, or whether he knew the sources of its aggadah separately. Of the smaller Midrashim he used the Heikhalot Rabbati, the Alfabet de-Ben Sira, the Sefer Zerubabel, the Baraita de-Ma'aseh Bereshit, [and many others] [...] The Zohar also draws from the Bible commentaries written by medieval rabbis, including Rashi, Abraham ibn Ezra, David Kimhi and even authorities as late as Nahmanides and