Cheng G, Zervopoulos P, Qian Z. A variant of radial measure capable of dealing with negative inputs and outputs in data envelopment analysis.
author: source: Date:2012-10-15
Cheng G, Zervopoulos P, Qian Z. A variant of radial measure capable of dealing with negative inputs and outputs in data envelopment analysis. European Journal of Operational Research (2012)
http://dx.doi.org/10.1016/j.ejor.2012.09.031.