%0 Journal Article %A O. V. Diaconescu %A M. N. Popa %T Lie algebras of operators and invariant $GL(2,\mathbb{R})$-integrals for Darboux type differential systems %J Buletinul Academiei de Ştiinţe a Republicii Moldova. Matematica %D 2006 %P 3-16 %N 3 %I mathdoc %U http://geodesic.mathdoc.fr/item/BASM_2006_3_a0/ %G en %F BASM_2006_3_a0