Airplanes, elevators, enclosed place, etc.
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Recommended book
Antony, M. M., Craske, M. G., & Barlow, D. H. (2006). Mastering your fears and phobias, 2nd Ed. - Workbook. Oxford University Press.
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Fear of Flying Clinic - Seattle WA. www.fearofflyingclinic.org
Reid Wilson, PhD - Fear of Flying Self-Help Program
Carbonell, D. A. (2017). Fear of flying workbook: Overcome your anticipatory anxiety and develop skills for flying with confidence. [Amazon]