Malinowskaa, A. B., & Torres, D. F. M. (2007). Nonessential Functionals in Multiobjective Optimal Control Problems. Proceedings of the Estonian Academy of Sciences. Physics, Mathematics, 56(4), 336-346. https://www.airitilibrary.com/Article/Detail?DocID=14060086-200712-201011080023-201011080023-336-346