Start with high-confidence gnosticism books, then narrow by subgenre or adjacent topics.
The Five Gospels
Robert W. Funk, Roy W. Hoover
The Nag Hammadi Scriptures
Marvin W. Meyer, James M. Robinson
Heretic
Catherine Nixey
Beyond Belief
Elaine Pagels
John of History, Baptist of Faith
James F. McGrath
Jung and the Lost Gospels
Stephan A Hoeller
Mary Magdalene Revealed
Meggan Watterson
The Magdalene Revolution
Andrew Harvey
Techgnosis
Erik Davis, Steve Wojtas
The Meaning of Mary Magdalene
Cynthia Bourgeault
Return of the Divine Sophia
Tricia McCannon
The Gnostic Gospels of Thomas, Mary & John
Thomas the Apostle
Pistis Sophia
G.R.S. Mead
The Lost Pillars of Enoch
Tobias Churton
The Law of Light
Lars Muhl
