1. The p-centre problem — Heuristic and optimal algorithms;Drezner;J. Oper. Res. Soc.,1984
2. On a multidimensional search technique and its application to the Euclidean one-centre problem;Dyer,1984
3. Optimal packing and covering in the plane are NP-complete;Fowler,1981
4. A best possible heuristic for the k-centre problem;Hochbaum,1983
5. Powers of graphs: A powerful approximation technique for bottleneck problems;Hochbaum,1984