Giorgio Ausiello Stefano Leonardi Alberto Marchetti-Spaccamela On Salesmen, Repairmen, Spiders, and Other Traveling Agents. 1-16 2000 conf/ciac/2000 CIAC http://dx.doi.org/10.1007/3-540-46521-9_1 db/conf/ciac/ciac2000.html#AusielloLM00