1. Rockafellar, R.T.: Convex Analysis. Princeton University Press, Princeton (1970)
2. Ansari, Q.H., Lalitha, C.S., Mehta, M.: Generalized Convexity, Nonsmooth Variational Inequalities, and Nonsmooth Optimization. CRC Press, Boca Raton (2014)
3. Cambini, A., Martein, L.: Generalized Convexity and Optimization. Springer, Berlin (2009)
4. Diewert, W.E.: Alternative characterizations of six kinds of quasiconcavity in the nondifferentiable case with applications to nonsmooth programming. In: Schaible, S., Ziemba, W.T. (eds.) Generalized Concavity in Optimization and Economics. Academic Press, New York (1981)
5. Hadjisavvas, N., Komlosi, S., Schaible, S.: Handbook of Generalized Convexity and Generalized Monotonicity. Springer, Boston (2005)