Tselkov, Veselin, Dragomir Pargov, and Rusin Petrov. Criteria of Computer System Security Assessment and Evaluation In nformation Aspects of Security and Development of Modern Societies, Edited by Velizar Shalamanov and Todor Tagarev. Sofia: AFCEA-Sofia, 1996.

Pargov, Dragomir, Veselin Tselkov, Rusin Petrov, and Iliya Kraytchev. Security in Computer Systems In Information Aspects of Security and Development of Modern Societies, Edited by Velizar Shalamanov and Todor Tagarev. Sofia, Bulgaria: AFSEA-Sofia, 1996.

Pargov, Dragomir, Veselin Tselkov, Rusin Petrov, and Iliya Kraytchev. Security in Computer Systems In  AFSEA-Sofia Information Aspects of Security and Development of Modern Societies, Edited by Velizar Shalamanov and Todor Tagarev. Sofia:, 1996.