Шибицька, Н. М., and Г. А. Тимофієва. “Information Technology of Questions Complication Determination”. Problems of Informatization and Control 2, no. 26 (June 22, 2009): 151–155. Accessed June 14, 2026. http://jrnl.kai.edu.ua/index.php/PIU/article/view/7001.