Valyi, I. (1987). Epsilon Solutions and Duality in Vector Optimization. In: Toward Interactive and Intelligent Decision Support Systems. Eds. Sawaragi, Y., Inoue, K., & Nakayama, H., pp. 417-426 Germany: Springer Berlin Heidelberg. ISBN 978-3-642-46607-610.1007/978-3-642-46607-6_45.