Salami, M. , Sobhani, F. , Ghazizadeh, M.. "Multistage Data Envelopment Analysis Model for Malmquist Productivity Index Using Grey's System Theory to Evaluate Performance of Electric Power Supply Chain in Iran". World Academy of Science, Engineering and Technology, Open Science Index 153, International Journal of Economics and Management Engineering (2019), 13(9), 1181 - 1192.