B. M. Mathers, L. Degenhardt, B. Phillips, L. Wiessing, M. Hickman, S. Strathdee, A. Wodak, et al., “Global Epidemiology of Injecting Drug Use and HIV among People who Inject Drugs: A Systematic Review,” Lancet, Vol. 372, No, 9651, 2008, pp. 1733-1745. doi:10.1016/S0140-6736(08)61311-2
 C. P. Archibald, G. C. Jayaraman, C. Major, D. M. Patrick, S. M. Houston and D. Sutherland, “Estimating the Size of Hand-to-Reach Population: A Novel Method Using HIV Testing Data Compared to Other Methods,” AIDS, Vol. 15, 2001, pp. s41-s48. doi:10.1097/00002030-200104003-00006
 K. L. DEHNE, M. ADELEKAN, A. CHATTERJEE and G. WEILER, “The Need for a Global Understanding of Epidemiological Data to Inform Human Immunodeficiency Virus (HIV) Prevention among Injecting Drug Users,” Bulletin on Narcotics, Vol. LIV, No. 1-2, 2002, pp. 117- 130.
 R. Muga, K. Langohr, J. Tor, A. Sanvisens, I. Serra and C. R. Rey-Joly, “Survival of HIV-Infected Injection Drug Users (IDUs) in the Highly Active Antiretroviral Therapy Era, Relative to Sex- and Age-Specific Survival of HIV-Un- infected IDUs,” Clinical Infectious Diseases, Vol. 45, No. 3, 2007, pp.370-376. doi:10.1086/519385
 Committee on the Prevention of HIV Infection among Injecting Drug Users in High-Risk Countries, “Preventing HIV Infection among Injecting Drug Users in High Risk Countries: An Assessment of the Evidence,” The National Academies Press, Washington, D.C., 2006.
 S. Zhang, P. Yan and C. Archibald, “Estimating the Size of IDU Population Using Needle Exchange Programs,” Proceedings of Statistics Canada Symposium 2004 Innovative Methods for Surveying Difficult-to-Reach Popultions, Statistics Canada, Ottawa, 2004, pp. 1-10.
 D. D. Heckathorn, “Extensions of Respondent-Driven sampling: Analyzing Continuous Variables and Controlling for Differential Recruitment,” Sociological Methodology, Vol. 31, No. 1, 2007, pp. 151-207. doi:10.1111/j.1467-9531.2007.00188.x
 K. J. Gile and M. S. Handcock, “Respondent-Driven sampling: An Assessment of Current Methodology,” Sociological Methodology, Vol. 40, No. 1, 2010, pp. 285-327. doi:10.1111/j.1467-9531.2010.01223.x
 M. J. Salganik and D. D. Heckathorn, “Sampling and Estimation in hidden Populations Using Respondent- driven Sampling,” Sociological Methodology, Vol. 34, No. 1, 2004, pp. 193-239. doi:10.1111/j.0081-1750.2004.00152.x
 Public Health Agency of Canada, “Harm Reduction and Injection Drug Use: An International Comparative Study of Contextual Factors Influencing the Development and Implementation of Relevant Policies and Program,” 2003, accessed on 18 March 2006. http://www.phac-aspc.gc.ca/hepc/pubs/hridu-rmudi/index-eng.php
 C. Strike, L. Leonard, M. Millson, S. Anstice, N. Berkeley and E. Medd, “Ontario Needle Exchange Programs: Best Practice Recommendations,” Toronto: Ontario Needle Exchange Coordinating Committee, 2006.
 C. L. Miller, M. Tyndall, P. Spittal, K. Li, A. Palepu and M. T. Schechter, “Risk-Taking Behaviors among Injecting Drug Users Who Obtain Syringes from Pharmacies, Fixed Sites, and Mobile Van Needle Exchanges,” Journal of Urban Health, Vol. 79, No. 2, 2002, pp. 257-265. doi:10.1093/jurban/79.2.257
 M. MacDonald, A. D. Wodak, R. Ali, N. Crofts, P. H. Cunningham, K. A. Dolan, M. Kelaher, W. M. Loxley, I. van Beek and J. M. Kaldor, “HIV Prevalence and Risk Behaviour in Needle Exchange Attenders: A National Study. The Collaboration of Australian Needle Exchanges,” The Medecal Journal of Australia, Vol. 166, No. 5, 1997, pp. 237-240.
 M. Peggy, T. Myers, L. Calzavara, E. Wallace, C. Major, and N. Degani, “Regional Variation in HIV Prevalence and Risk Behaviours in Ontario Injection Drug Users,” Canadian Journal of Public Health, Vol. 94, No. 6, 2003, pp. 431-435.