OT = Old Testament - 39 books. The first 5 are called Torah, the book of Moses.
NG = The New Gospel of Jesus Christ - Prediction of the last prophet to Isreal (Isaiah 7:14)
Quran = The last revelation from God - Fulfilment of a promise, God had made in the OT to Prophet Abraham concerning Ishmael (OT-Genesis 17:20) - Same as the Torah (Koran 87:19)