1. An, L.T.H., Belghiti, M.T., Tao, P.D.: A new efficient algorithm based on DC programming and DCA for clustering. J. Glob. Optim. 27, 503–608 (2007)
2. An, L.T.H., Minh, L.H., Tao, P.D.: New and efficient DCA based algorithms for minimum sum-of-squares clustering. Pattern Recognit. 47, 388–401 (2014)
3. An, L.T.H., Minh, L.H.: Optimization based DC programming and DCA for hierarchical clustering. Eur. J. Oper. Res. 183, 1067–1085 (2007)
4. An, L.T.H., Tao, P.D.: Convex analysis approach to D.C. programming: theory, algorithms and applications. Acta Math. Vietnam 22, 289–355 (1997)
5. Bagirov, A.: Derivative-free methods for unconstrained nonsmooth optimization and its numerical analysis. Investig. Oper. 19, 75–93 (1999)