1. Viliam L. (2009) “CRM architecture for effective enterprise relationship marketing”, Journa of Information, Control and Management Systems 1: 7-11.
2. Wycislik M. and Ellis C. (2017) “The best free cloud storage service 2017”, retrieved from http://www.techradar.com/news/the-best-free-cloud-storage.
3. Janis A., Bubenko jr. (2007) “From Information Algebra to Enterprise Modelling and Ontologies - a Historical Perspective on Modelling for Information Systems”, in John Krogstie et al. (eds) Conceptual Modelling in Information Systems Engineering, pp. 1-18.
4. Museum of Dionysius Frescoes, http://www.dionisy.com/monastery/. In Russian..
5. Lelekova O. and Naumova M. (1989) “Wall paintings by Dionisius in the Cathedral of the Nativity of the Virgin at the Ferapontov Monastery (results of the restoration investigations)”, in G. Popov (ed.) Old Russian art. Art heritages of North Russia, Moscow, Nauka, pp.63-68. ISBN 5-02-012713-2. In Russian..