1. M. L. Balinski, On finding integer solution to linear programs, in, Proc. of the IBM Scientific Computing Symposium on Combinatorial Problems, 1966, 225, 248
2. The uncapacitated facility location problem;Cornuejols,1990
3. Improved approximation algorithms for uncapacitated facility location;Chudak,1998
4. U. Feige, A threshold of lnn, in, 28th ACM Symposium on Theory of Computing, 1996, 314, 318
5. J. Håstad, Some optimal inapproximability results, in, 29th ACM Symposium on Theory of Computing, 1997, 1, 10