Vorobjov, Sigrid, Don C. Des Jarlais, Katri Abel-Ollo, Ave Talu, Kristi Rüütel, and Anneli Uusküla. "Socio-demographic factors, health risks and harms associated with early initiation of injection among people who inject drugs in Tallinn, Estonia: evidence from cross-sectional surveys." The International journal on drug policy 24, no. 2 (2013): 150-5.