The Unseen Realm: Recovering the Supernatural Worldview of the Bible
The "sons of God" are his Divine Council.
Recommended reading: The Unseen Realm, by Dr. Michael Heiser. Or really just anything Dr. Heiser does. The Divine Council is kind of his thing.
See also: Spiritual Beings playlist, by The Bible Project.
I got this directly from Dr. Michael S. Heiser's book entitled The Unseen Realm: Recovering the supernatural worldview of the Bible .
Michael Heiser has an exhaustive treatment of all of these forms in The Unseen Realm .
I hail from /r/AcademicBiblical and /r/AskBibleScholars and this is a very good comment.
The best modern source for this material is The Unseen Realm by Michael S. Heiser.