^Griffin, Joe; Tyrrell, Ivan (1998). Psychotherapy, Counselling and the Human Givens (Organising Idea). European Therapy Studies Institute. ISBN978-1899398959.
^Cooper, Cary L.; Kinder, Andrew (2012). Hughes, Rick (ed.). International handbook of workplace trauma support (1 ed.). Chichester, West Sussex: Wiley-Blackwell. pp. Chapter 9. ISBN978-0-470-97413-1.