Bulitko, V. V. and Bulitko, V. K. (1998) “On a criterion of $NP$-completeness”, Ukrains’kyi Matematychnyi Zhurnal, 50(12), pp. 1686–1691. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/4788 (Accessed: 19May2024).