@article{Heckathorn1997,
author = {Heckathorn, D.D.},
title= {Respondent-driven sampling: A new approach to the study of hidden populations},
year = {1997},
doi = {10.1525/sp.1997.44.2.03x0221m},
journal = {Social Problems},
volume = {44},
number = {2},
pages = {174--199},
}