1. Cabinet of Ministers of Ukraine: Fight against corruption. https://www.kmu.gov.ua/diyalnist/reformi/verhovenstvo-prava-ta-borotba-z-korupciyeyu/borotba-z-korupciyeyu
2. Transparency International: Corruption Perceptions Index 2020. https://images.transparencycdn.org/images/2020_Report_CPI_EN.pdf
3. Dreher A, Schneider F (2006) Coruption and the Shadow Economy: an Empirical Analysis, CESifo Working Papers Series 1613, CESifo Group Munich
4. Elgin C, Oztunali O (2013) Institutions, Informal Economy and Economic Development, Working Papers 2013/03, Bogazici University, Department of Economics
5. Frey R, Van Hannemann P (2003) The Analysis of the second economy. The Economics of the shadow economy, London