Book of Enoch: Angels, Watchers and Nephilim.

The Book of Enoch contains accounts of the Watchers, a class of angel, who came to earth, taught humans weapons, alchemy, spell potions, sorcery, astrology, and astronomy. The Watchers also slept with human women and produced the Nephilim. For this, they were punished and cast into Tartarus. This is also mentioned in the New Testament. This is an easy to read translation of The Book of Enoch with additional information on angels, Watchers, and Nephilim.