1. Calinescu, G., Chekuri, C., Pal, M., Vondrak, J.: Maximizing a submodular set function subject to a matroid constraint. In: Proceedings of the 12th International Conference on Integer Programming and Combinatorial Optimization (IPCO 2007), pp. 182–196 (2007)
2. Du, D.-Z., Graham, R.L., Pardalos, P.M., Wan, P.-J., Wu, W., Zhao, W.: Analysis of greedy approximations with nonsubmodular potential functions. In: Proceedings of the 19th Annual ACM-SIAM Symposium on Dicrete Algorithms (SODA). San Francisco, USA, Jan 20–22, pp. 167–175 (2008)
3. Du D.-Z., Gao B., Wu W.: A special case for subset interconnection designs. Discret. Appl. Math. 78, 51–60 (1997)
4. Du, D.-Z., Ko, K.-I., Hu, X.: Design and Analysis of Approximation Algorithms, Lecture Notes (2008)
5. Du D.-Z., Ko K.-I.: Theory of Computational Complexity. Wiley, New York (2000)