The Book of the Giants by W. B. Henning

The Book of the Giants. The acts of the Giant Ogias (Og of Bashan)
The Manichean text. Translation by W. B. Henning

Plus the Dead Sea Scrolls Book of Giants Text.

Ogias the Giant is thought to have been based on the Book of Enoch, a possibly pseudepigraphical Jewish work from the 3rd Century B.C., itself based on an obscure passage from concerning Nephilim, which, in the Enoch version, are the offspring of fallen angels they saw the beauty of the daughters of men, married them, and thus fathered Giants in the land. The book concerns itself with filling in the details about the giants and their offspring that the Book of Enoch is lacking.

"Now the giants were upon the earth in those days; and after that when the sons of God were wont to go in to the daughters of men, they bore children to them, those were the giants of old, the men of renown."

Book Link: The Book of the Giants by W. B. Henning