O. V. Diaconescu, “Multi-dimensional Darboux type differential systems with quadratic nonlinearities”, Bul. Acad. Ştiinţe Repub. Mold. Mat., 2007, no. 1, 95–100
O. V. Diaconescu, M. N. Popa, “Lie algebras of operators and invariant $GL(2,\mathbb{R})$-integrals for Darboux type differential systems”, Bul. Acad. Ştiinţe Repub. Mold. Mat., 2006, no. 3, 3–16
