@article{DBLP:journals/siamcomp/AryaGKMMP04,
  author    = {Vijay Arya and
               Naveen Garg and
               Rohit Khandekar and
               Adam Meyerson and
               Kamesh Munagala and
               Vinayaka Pandit},
  title     = {Local Search Heuristics for k-Median and Facility Location
               Problems},
  journal   = {SIAM J. Comput.},
  volume    = {33},
  number    = {3},
  year      = {2004},
  pages     = {544-562},
}
@article{DBLP:journals/jacm/JainV01,
  author    = {Kamal Jain and
               Vijay V. Vazirani},
  title     = {Approximation algorithms for metric facility location and
               {\it }-Median problems using the primal-dual schema and
               Lagrangian relaxation},
  journal   = {J. ACM},
  volume    = {48},
  number    = {2},
  year      = {2001},
  pages     = {274-296},
}
@misc{ williamson-primaldual,
  author = "D. Williamson",
  title = "The primal-dual method for approximation algorithms",
  text = "D.P. Williamson, The primal-dual method for approximation algorithms. Mathematical
    Programming , to appear. 14",
  url = "citeseer.ist.psu.edu/689026.html"
  }