1. Health Unit, RAND Corporation, 1776 Main Street, P.O. Box 2138, Santa Monica, CA 90407, USA
2. Health Unit, RAND Corporation, Arlington, VA 22202, USA
3. AIDS Healthcare Foundation, Los Angeles, CA 90028, USA
4. Infectious Diseases Section, Greater Los Angeles Veterans Administration, Los Angeles, CA 90073, USA
5. Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Los Angeles, CA 90509, USA