%0 Journal Article %A Natalia Neagu %A Victor Orlov %A Mihail Popa %T Invariant conditions of stability of unperturbed motion governed by critical differential systems $s(1,2,3)$ %J Buletinul Academiei de Ştiinţe a Republicii Moldova. Matematica %D 2019 %P 137-153 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/BASM_2019_2_a8/ %G en %F BASM_2019_2_a8