BIBCYT http://bibcyt.ucla.edu.ve/cgi-win/be_alex.exe?Ultimo&Nombrebd=BIBCYT UCLA - Biblioteca de Ciencias y Tecnologia Felix Morales Bueno Levin, Asaf levinas@tx.technion.ac.il P Principal A better approximation algorithm for the budget prize collecting tree problem Vol: 32 pp. 316-319 Levin, Asaf levinas@tx.technion.ac.il P Principal Strongly polynomial-time approximation for a class of bicriteria problems Vol: 32 pp. 530-534