1. Altinkemer, K., Gavish, B.: Heuristics with constant error guarantees for the design of tree networks. Management Science 34, 331–341 (1988)
2. Cai, Z.: Improved algorithm for multicast routing and binary fingerprint vector clustering. Master’s thesis, Department of Computing Science, University of Alberta, June 16 (2004)
3. Cai, Z., Lin, G.-H., Xue, G.L.: Improved approximation algorithms for the capacitated multicast routing problem. Technical Report TR04-12, Department of Computing Science, University of Alberta (July 2004)
4. Gröpl, C., Hougardy, S., Nierhoff, T., Prömel, H.J.: Approximation algorithms for the Steiner tree problem in graphs. In: Du, D.-Z., Cheng, X. (eds.) Steiner Trees in Industries, pp. 235–279. Kluwer Academic Publishers, Dordrecht (2001)
5. Gu, J., Hu, X.D., Jia, X., Zhang, M.-H.: Routing algorithm for multicast under multi-tree model in optical networks. Theoretical Computer Science 314, 293–301 (2004)