ŞUBĂ, Alexandru, and Silvia TURUTA. “CUBIC DIFFERENTIAL SYSTEMS WITH A WEAK FOCUS AND A REAL INVARIANT STRAIGHT LINE OF MAXIMAL ALGEBRAIC MULTIPLICITY ”. Acta et Commentationes Exact and Natural Sciences 4, no. 2 (July 9, 2019): 119-130. Accessed December 7, 2021. https://revista.ust.md/index.php/acta_exacte/article/view/359.