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Luu, Do Van and Nguyen, Manh-Hung (2004) On necessary conditions for efficiency in directionally differentiable multiobjective optimization problems. Nonlinear functional analysis and applications (12). pp. 439-453.
Luu, Do Van and Nguyen, Manh-Hung (2004) Invexity of constraint maps in mathematical programs. Nonlinear functional analysis and applications (9). pp. 289-304.