Necessary and sufficient conditions for the efficient solutions of nondifferentiable multiobjective problems. - Yo Ishizuka; Kiyotaka Shimizu (IEEE Trans. Syst. Man Cybern., 1984)

Double penalty method for bilevel optimization problems. - Yo Ishizuka; Eitaro Aiyoshi (Ann. Oper. Res., 1992)

Mean and variance of waiting time and their optimization for alternating traffic control systems. - Hideaki Yamashita; Yo Ishizuka; Shigemichi Suzuki (Math. Program., 2006)