On the Sign of Solutions of Systems of Ordinary Differential Equations
We show that Theorems 1 and 3 in A. G. Gritsai's paper “Monotonicity properties of solutions of systems of nonlinear differential equations” published in the collection of works Approximate and Qualitative Methods in the Theory of Differential and Functional Differential-Equations (Institute of Mathematics, Ukrainian Academy of Sciences, Kiev, 1979) are not true in the formulation presented.
English version (Springer): Ukrainian Mathematical Journal 54 (2002), no. 9, pp 1547-1549.
Citation Example: Kalinowski J. On the Sign of Solutions of Systems of Ordinary Differential Equations // Ukr. Mat. Zh. - 2002. - 54, № 9. - pp. 1282-1283.