One is a great deal less anxious if one feels perfectly free to be anxious, and the same may be said of guilt.

Alan Wattsx.com

John P. Forsyth The Mindfulness and Acceptance Workbook for Anxiety: A Guide to Breaking Free from Anxiety, Phobias, and Worry Using Acceptance and Commitment Therapy

David R. Hawkins Letting Go: The Pathway of Surrender

Paul David At Last A Life