Item from Mathematical Reviews (American Mathematical Society)--access
their stable url through the AMS database via an institutional library:
MR1683473 (2000a:90048) Avella, Pasquale; Sforza, Antonio Logical
reduction tests for the $p$-median problem. Advances in combinatorial
optimization (London, 1996). Ann. Oper. Res. 86 (1999), 105--115.
(Reviewer: Sandra L. Arlinghaus) 90C27 (90B80)