1. Biopac,
http://www.biopac.com
2. Mental Health Foundation in UK,
http://www.mentalhealth.org.uk
3. The Organisation for Economic Co-operation and Development (OECD),
http://www.oecd.org
4. World Health Organization (WHO),
http://www.who.org
5. Beck, A.T.: Cognitive therapy and the emotional disorders. International Universities Press, Inc., Madison (1975)