were widely noted, but perhaps not widely read. In 1972 a cache of ancient Qur'ans in a mosque in Sana'a, Yemen was discovered – commonly known as the Sana'a manuscripts. The German scholar Gerd R. Puin and his research team, who investigated these Quran fragments for many years, made approximately 35,000 microfilm photographs of the manuscripts, which he dated to early part of the 8th century. Puin has not published the entirety of his work, but noted unconventional verse orderings, minor textual variations, and rare styles of orthography. He also suggested that some of the parchments were palimpsests which had been reused. Puin believed that this implied an evolving text as opposed to a fixed one. Keith Small, in Textual Criticism and Qur’ān Manuscripts, has concluded that it is not possible to develop a reliable critical text of the Quran based on the sources currently available. The Corpus Coranicum project is an ongoing effort to develop a critical edition of the Quran. Differences and similarities with the Bible Skeptical scholars account for the many similarities between the Quran and the Jewish and Hebrew Scriptures by saying that Muhammad was teaching what he believed to be a universal history, as he had heard it from the Jews and Christians he had encountered in Arabia and on his travels – as well as his exposure to the Hanif tradition by way of his paternal-grandfather, Abdul Muttalib. These scholars also disagree with the Islamic belief that the whole of the Quran is addressed by God to humankind. They note that there are numerous passages where God is directly addressed, or mentioned in the third person, or where the narrator swears by various entities, including God. The Quranic account, however, differs significantly regarding the crucifixion and death of Jesus. Similarities with Apocryphal legends Aside from the Bible, Quran relies on several Apocryphal sources, like the Protoevangelium of James, Gospel of Pseudo-Matthew, and several infancy gospels. Several narratives rely on Jewish Midrash Tanhuma legends, like the narrative of Cain learning to bury the body of Abel in Surah 5:31. Varying codices and the start of the canonization Before Uthman established the canon of the Quran, there may have been different versions or codices in complete state, though none has yet been discovered. Such codices as may exist never gained general approval and were viewed by Muslims as individuals' personal copies. With respect to partial codices,