1. RTI International 3040 Cornwallis Road PO Box 12194,
Research Triangle Park NC 27709-2194, USA,
2. School of Information and Library Science University
of North Carolina Chapel Hill, NC 27599-3360, USA,
3. epartment of Epidemiology School of Public Health University
of North Carolina Chapel Hill, NC 27599-7435, USA
4. Institute for Medicine and Public Health Vanderbilt
University Nashville, TN 37203-1738, USA
5. Drug Information Services Department of Pharmacy UNC
Hospitals Chapel Hill, NC 27599-7600, USA
6. Cecil G. Sheps Center for Health Services Research University
of North Carolina Chapel Hill, NC 27599-7590, USA