On the solution stability of variational inequalities. - Bui Trong Kien; M.-M. Wong (J. Glob. Optim., 2007)

On the solution existence of pseudomonotone variational inequalities. - Bui Trong Kien; Jen-Chih Yao; Nguyen Dong Yen (J. Glob. Optim., 2008)

Necessary Conditions for Multiobjective Optimal Control Problems with Free End-Time. - Bui Trong Kien; Ngai-Ching Wong; Jen-Chih Yao (SIAM J. Control. Optim., 2008)

Subgradients of value functions in parametric dynamic programming. - Bui Trong Kien; Yeong-Cheng Liou; Ngai-Ching Wong; Jen-Chih Yao (Eur. J. Oper. Res., 2009)

Degree theory for generalized variational inequalities and applications. - Bui Trong Kien; M.-M. Wong; Ngai-Ching Wong; Jen-Chih Yao (Eur. J. Oper. Res., 2009)

Lower Semicontinuity of the Solution Set to a Parametric Optimal Control Problem. - Bui Trong Kien; Nguyen Thi Toan; M.-M. Wong; Jen-Chih Yao (SIAM J. Control. Optim., 2012)

Second-Order Necessary Optimality Conditions for a Class of Semilinear Elliptic Optimal Control Problems with Mixed Pointwise Constraints. - Bui Trong Kien; V. H. Nhu (SIAM J. Control. Optim., 2014)

Second-Order Necessary Optimality Conditions for a Class of Optimal Control Problems Governed by Partial Differential Equations with Pure State Constraints. - Bui Trong Kien; Vu Huu Nhu; Arnd Rösch (J. Optim. Theory Appl., 2015)

Further Results on Subgradients of the Value Function to a Parametric Optimal Control Problem. - Nguyen Huy Chieu; Bui Trong Kien; Nguyen Thi Toan (J. Optim. Theory Appl., 2016)

Second-Order Optimality Conditions for Boundary Control Problems with Mixed Pointwise Constraints. - Nguyen Hai Son; Bui Trong Kien; Arnd Rösch (SIAM J. Optim., 2016)

Pontryagin's Principle for Optimal Control Problem Governed by 3D Navier-Stokes Equations. - Bui Trong Kien; Arnd Rösch; Daniel Wachsmuth (J. Optim. Theory Appl., 2017)

Second-Order KKT Optimality Conditions for MultiObjective Optimal Control Problems. - Bui Trong Kien; Nguyen Van Tuyen; Jen-Chih Yao (SIAM J. Control. Optim., 2018)

Second-Order Optimality Conditions for Multiobjective Optimal Control Problems with Mixed Pointwise Constraints and Free Right End Point. - Bui Trong Kien; Xiaolong Qin; Ching-Feng Wen; Jen-Chih Yao (SIAM J. Control. Optim., 2020)

The Galerkin Method and Regularization for Variational Inequalities in Reflexive Banach Spaces. - Bui Trong Kien; Xiaolong Qin; Ching-Feng Wen; Jen-Chih Yao (J. Optim. Theory Appl., 2021)

A Class of Quasilinear Equations with Riemann-Liouville Derivatives and Bounded Operators. - Vladimir E. Fedorov; Mikhail M. Turov; Bui Trong Kien (Axioms, 2022)

Optimal Control Problems Governed by Fractional Differential Equations with Control Constraints. - Bui Trong Kien; Vladimir E. Fedorov; T. D. Phuong (SIAM J. Control. Optim., 2022)

On the second-order optimality conditions for multi-objective optimal control problems with mixed pointwise constraints. - Bui Trong Kien; Trinh Duy Binh (J. Glob. Optim., 2023)

FEM for Semilinear Elliptic Optimal Control with Nonlinear and Mixed Constraints. - Bui Trong Kien; Arnd Rösch; Nguyen Hai Son; Nguyen Van Tuyen (J. Optim. Theory Appl., 2023)