XU, J., 		ZERVOPOULOS, P., 		QIAN, Z., & 		CHENG, G.
(2012).
 A UNIVERSAL SOLUTION FOR UNITS - INVARIANCE IN DATA ENVELOPMENT ANALYSIS.
<em>Theoretical And Practical Research In Economic Fields, 3</em>(2), 121-128.
Retrieved from <a href="https://journals.aserspublishing.eu/tpref/article/view/1173" target="_new">https://journals.aserspublishing.eu/tpref/article/view/1173</a>