A lot of work is being done on what the Qur’an refers to [it is largely incomprehensible without exegesis]. Gabriel Said Reynolds has helpfully summarized some of these developments in this article. Another helpful source is this Wikipedia entry on the Syro-Aramaic Reading of the Koran. I came across another example of this dependence on the Bible today in an article about the Corpus Coranicum project:
Gerd-R. Puin, a retired professor of Arabic studies at Germany’s Saarland University, has been working for decades on a trove of Korans from a mosque in Yemen — possibly the oldest ones in existence. Because they were primarily memory aids, early Korans were written in a vowel-less “skeleton” language. Deciphering those clusters of consonants requires a sense of what languages and what cultural and religious traditions Mohammed and his earliest followers were borrowing from and reacting against. Much of the wording and imagery of the Koran are borrowed from Christian and Jewish texts, Puin argues. In fact, he says, much of the Koran is incomprehensible unless read alongside those earlier texts. As an example, he points to the term “sakina,” which Muslim scholars have translated as a spirit of calm — Puin argues that it only makes sense as a descendant of the Hebrew term “shekhinah,” which means the presence of God. The more one studies its historical context, Puin argues, the harder it is to resist the sense that the Koran itself was, at least in part, pieced together from parts of other religions.
I would love to see a version of the Qur’an in the future that fully cross-references these notional Christian sources: liturgies, Creeds and the Bible itself. That should be fascinating.