1. Löhne, A.: Vector Optimization with Infimum and Supremum. Vector Optimization. Springer, Berlin (2011)
2. Borwein, J.M.: Multivalued convexity and optimization: a unified approach to inequality and equality constraints. Math. Program. 13, 183–199 (1977)
3. Borwein, J.M.: A Lagrange multiplier theorem and a sandwich theorem for convex relations. Math. Scand. 48(2), 189–204 (1981)
4. Borwein, J.M.: Convex relations in analysis and optimization. In: Schaible, S., Ziemba, W.T. (eds.) Generalized Concavity in Optimization and Economics, pp. 335–377. Academic Press, New York (1981)
5. Oettli, W.: Optimality conditions for programming problems involving multivalued mappings. In: Schaible, S., Ziemba, W.T. (eds.) Generalized Concavity in Optimization and Economics, pp. 227–238. Academic Press, New York (1981)