Columbia subject headings:
Harvard subject headings:
HIV infections--United States--Epidemiology--Methodology.
HIV infections--United States--Longitudinal studies--Methodology.
Intravenous drug abuse--Research--United States--Methodology.
Intravenous drug abusers--Diseases--United States--Longitudinal studies--Methodology.
Princeton subject headings:
HIV infections--United States--Epidemiology--Methodology.
HIV infections--United States--Longitudinal studies--Methodology.
Intravenous drug abuse--Research--United States--Methodology.
Intravenous drug abusers--Diseases--United States--Longitudinal studies--Methodology.