Schmittner John, Schroeder Jennifer R, Epstein David H, Preston Kenzie L
National Institutes of Health, National Institute on Drug Abuse, Intramural Research Program, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
BMJ. 2004 Nov 6;329(7474):1075. doi: 10.1136/bmj.329.7474.1075.