1. Agrawal, A., Klein, P., Ravi, R.: When trees collide: An approximation algorithm for the generalized Steiner problem on networks. SIAM J. Comput, 24 (3), 440–456 (1995)
2. Archer, A., Williamson, D.P.: Faster approximation algorithms for the minimum latency problem. In: Proceedings of 14th ACM-SIAM Symp. on Discrete Algorithms (SODA), 2003, pp. 88–96
3. Arora, S.: Polynomial-time approximation schemes for Euclidean TSP and other geometric problems. J. ACM 45 (5), 1–30, (1998) Preliminary versions in Proceedings of 37th IEEE Symp. on Foundations of Computer Science (FOCS), pp. 2–12, 1996, and in Proceedings of 38th IEEE Symp. on Foundations of Computer Science (FOCS), 1997, pp. 554–563
4. Arya, S., Ramesh, H.: 2.5-factor approximation algorithm for the k-MST problem. Information Processing Letters 65 (3), 117–118 (1998)
5. Awerbuch, B., Azar, Y., Blum, A., Vempala, S.: New approximation guarantees for minimum weight k-trees and prize-collecting salesmen. SIAM J. Comput. 28 (1), 254–262 (1998)