ANCIENT ORIGINS: The Terrifying Doomsday Prophecy of the Tiburtine Sibyl (NATALIA KLIMCZAK). A pretty good essay on the ancient sibylline traditions, but it could be a little more lucid in places. As it says, the Sibyl was a legendary pagan Greek prophetess (or prophetesses). She was co-opted and multiplied by the Romans, still pagan, then adopted as a prophetess in Jewish tradition, then in turn by Christians. There are many ancient books of Sibylline Oracles, but these are all written by Jews or Christians. Nothing remains of the original Roman Sibylline Oracles except the odd quotation.
One important omission in this essay is information on where to read the various books of Sibylline Oracles in English translation. The bulk of them was translated with introduction by John Collins in volume one of Charlesworth's Old Testament Pseudepigrapha (Doubleday, 1983). (I don't have the page numbers handy.) The Tiburtine Sibyl has been translated into English with introduction recently by Rieuwerd Buitenwerf in volume one of Old Testament Pseudepigrapha: More Noncanonical Scriptures (ed. Bauckham, Davila, and Panayotov; Eerdmans, 2013), pp. 176-88. And another translation of the same work, this one by Stephen Shoemaker, is coming out in August of 2016 in volume one of New Testament Apocrypha: More Noncanonical Scriptures (ed. Tony Burke and Brent Landau). Enjoy.