Cioban, Mitrofan, Dumitru Cozma, and Leonid Dohotaru. “International Symposium "Actual Problems of Mathematics and Informatics" Dedicated to the 90th Birthday of Professor Ion Valutse”. Acta et Commentationes Exact and Natural Sciences 10, no. 2 (January 12, 2021): 117–124. Accessed September 28, 2021. https://revista.ust.md/index.php/acta_exacte/article/view/601.