Cooper, Mick (2016-08-25). The Handbook of Pluralistic Counselling and Psychotherapy. SAGE. ISBN978-1-4739-0398-2. “... Outcome Questionnaire-45.2 System (OQ: Lambert, 2010) Michael Lambert is the pioneer of systemic feedback, evolving the idea of outcome measurement to a ‘real time’ feedback process with a proven track record of improving outcomes.”
Lambert, Michael J.; Burlingame, Gary M.; Umphress, Val; Hansen, Nathan B.; Vermeersch, David A.; Clouse, Glenn C.; Yanchar, Stephen C. (1996). "The Reliability and Validity of the Outcome Questionnaire". Clinical Psychology & Psychotherapy. 3 (4): 249–258. doi:10.1002/(SICI)1099-0879(199612)3:4<249::AID-CPP106>3.0.CO;2-S. ISSN1063-3995.
Lambert, Michael J.; Burlingame, Gary M.; Umphress, Val; Hansen, Nathan B.; Vermeersch, David A.; Clouse, Glenn C.; Yanchar, Stephen C. (1996). "The Reliability and Validity of the Outcome Questionnaire". Clinical Psychology & Psychotherapy. 3 (4): 249–258. doi:10.1002/(SICI)1099-0879(199612)3:4<249::AID-CPP106>3.0.CO;2-S. ISSN1063-3995.