Helpful links listed in alphabetical order:
Eckhart Teachings – Echkart Tolle
Foundation for A Course in Miracles
Infinity Institute – Robert Adams
Life Without a Centre – Jeff Foster
One Who Wakes – John Mark Stroud
Paul Brunton Philosophic Foundation
Plum Village – Thich Nhat Hahn
The Awakened Heart of Chris Celine
The Freedom Religion Press – Michael Langford
The Infinite Way – Joel Goldsmith
Untethered Soul – Michael Singer