Maruşciac, I. “On Fritz John Type Optimality Criterion in Multi-Objective Optimization”. Anal. Numér. Théor. Approx. 11, no. 1 (August 1, 1982): 109-114. Accessed November 29, 2021. https://ictp.acad.ro/jnaat/journal/article/view/1982-vol11-nos1-2-art13.