On generalized Ekeland's variational principle and equivalent formulations for set-valued mappings. - Phan Quoc Khanh; Dinh Ngoc Quy (J. Glob. Optim., 2011)

On Ekeland's Variational Principle for Pareto Minima of Set-Valued Mappings. - Phan Quoc Khanh; Dinh Ngoc Quy (J. Optim. Theory Appl., 2012)

Versions of Ekeland's variational principle involving set perturbations. - Phan Quoc Khanh; Dinh Ngoc Quy (J. Glob. Optim., 2013)