G.I. Gurdjieff
Most (all?) of Gurdjieff’s works are still under copyright and not available online.
Kurma Purana
https://archive.org/details/kurma-purana-full-parts-1-and-2/page/n5/mode/2up
Private Dowding
https://archive.org/details/PrivateDowding
St. Augustine
https://archive.org/details/confessionsofsta00augu
The Bible (KJV)
https://www.kingjamesbibleonline.org
The Seth Material
The Seth Material is still under copyright and not available online.
The Urantia Book
https://www.urantia.org/urantia-book-standardized/urantia-book