1. Anon. (2005). Results from the 2004 National Survey on Drug Use and Health: National findings. Substance Abuse and Mental Health Services Administration, Department of Health and Human Services, Office of Applied Studies, Rockville, MD, p.310.
2. Endogenous opiates and behavior: 2004
3. Coupling of D2 dopamine receptors to G-proteins in solubilized preparations of bovine caudate nucleus
4. Major increases in opioid analgesic abuse in the United States: Concerns and strategies