1. Centre for the Study of Democracy (2002)Corruption, Trafficking and Institutional Reform: Prevention of Trans‐Border Crime in Bulgaria (2001–2002)(Sofia: Centre for the Study of Democracy)
2. Freedom House (2000)Nations in Transit 1999–2000⟨http://www.freedomhouse.org⟩
3. Naylor RT (2002)Wages of Crime: Black Markets, Illegal Finance, and the Underworld Economy(Ithaca, NY: Cornell University Press)