ZALMAI G.J. Proper efficiency conditions and duality models for nonsmooth multiobjective fractional programming problems with operator constraints, part I: Theory. Utilitas Mathematica , [S. l.], v. 50, 1996. Disponível em: https://utilitasmathematica.com/index.php/Index/article/view/26. Acesso em: 8 may. 2026.