Martinez MJ and YJ Nakanishi (2004). “Productivity Analysis in Heterogeneous Operating Conditions: Data Envelopment Analysis Method Applied to the U.S. Heavy Rail Industry.” Transportation Research Record 1872: 19-27.
Martinez MJ and YJ Nakanishi (2004). “Productivity Analysis in Heterogeneous Operating Conditions: Data Envelopment Analysis Method Applied to the U.S. Heavy Rail Industry.” Transportation Research Record 1872: 19-27.