1. Letters to the editor Silk Road: Ebay for drugs;Barratt;Addiction,2012
2. Beyond recruitment? Participatory online research with people who use drugs;Barratt;International Journal of Internet Research Ethics,2010
3. Qualitative case study methodology: Study design and implementation for novice researchers;Baxter;The Qualitative Report,2008
4. Outsiders: Studies in the sociology of deviance;Becker,1963
5. Bitcoin. (2011). Bitcoin. Bitcoin P2P digital currency. Retrieved from http://bitcoin.org/ (27.09.12).