For centuries, most scholarly knowledge of Gnosticism was limited to the anti-heretical writings of orthodox Christian figures such as Irenaeus of Lyons and Hippolytus of Rome. There was a renewed interest in Gnosticism after the 1945 discovery of Egypt's Nag Hammadi library, a collection of rare early Christian and Gnostic texts, including the Gospel of Thomas and the Apocryphon of John. A major question in scholarly research is the qualification of Gnosticism as either an interreligious phenomenon or as an independent religion. Scholars have acknowledged the influence of sources such as Hellenistic Judaism, Zoroastrianism, and Platonism, and some have noted possible links to Buddhism and Hinduism, though the evidence of direct influence from the latter sources is inconclusive.