1. American Pet Products Manufacturers Association, 2008. 2007/2008 APPMA national pet owners survey. Available at: http://www.americanpetproducts.org. Accessed February 13, 2008.
2. Diagnostic and statistical manual of mental disorders: DSM-IV-TR,2000
3. American Veterinary Medical Association, 2007. Guidelines for animal-assisted activity, animal-assisted therapy, and resident animal programs. Available at: http://www.avma.org/issues/policy/animal_assisted_guidelines.asp. Accessed December 13, 2009.
4. Why do people love their pets?;Archer;Evol. Hum. Behav,1997
5. Australian Bureau of Statistics, 1995. Australian social trends, Cat. no. 4102.0. Available at: http://www.abs.gov.edu/ausstats/. Accessed February 13, 2009.