1. Arora, S., Karakostas, G.: A $$2 + \epsilon $$ approximation algorithm for the $$k$$-MST problem. In: Proceedings of the 11th Annual ACM-SIAM Symposium on Discrete Algorithms (SODA), pp. 754–759 (2000)
2. Awerbuch, B., Azar, Y., Blum, A., Vempala, S.: Improved approximation guarantees for minimum-weight $$k$$-trees and prize-collecting salesmen. SIAM J. Copmput. 28(1), 254–262 (1998)
3. Bansal, N., Blum, A., Chawla, S., Meyerson, A.: Approximation algorithms for deadline-tsp and vehicle routing with time-windows. In: Proceedings of the 36th Annual ACM Symposium on Theory of Computing (STOC), pp. 166–174 (2004)
4. Blesa, M.J., Xhafa, F.: A C++ implementation of tabu search for $$k$$-cardinality tree problem based on generic programming and component reuse. In: Proceedings of Net. ObjectDays Forum, pp. 648–652. Erfurt, Germany (2000)
5. Blum, A., Chawla, S., Karger, D.R., Lane, T., Meyerson, A., Minkoff, M.: Approximation algorithms for orienteering and discounted-reward TSP. SIAM J. Comput. 37(2), 653–670 (2007)