Isto Aho New polynomial-time instances to various knapsack-type problems. 199-228 2002 53 Fundam. Inform. 3-4 http://iospress.metapress.com/openurl.asp?genre=article&issn=0169-2968&volume=53&issue=3&spage=199 db/journals/fuin/fuin53.html#Aho02