TY  - JOUR
A1  - Heckathorn, D.D.
A1  - Semaan, S.
A1  - Broadhead, R.S.
A1  - Hughes, J.J.
T1  - Extensions of respondent-driven sampling: A new approach to the study of injection drug users aged 18–25
Y1  - 2002
DO  - 10.1023/A:1014528612685
JF  - AIDS & Behavior 
VL  - 6
IS  - 1

ER  -