“…The network DEA models have been extended to allow different types of internal structure. Kao [40] classified the network DEA models into nine types, i.e., the independent model by Zhu [38], the system distance measure model by Chen et al [41], the process distance measure model by Chen et al [42], the factor distance measure model by Chen [43], the slacks-based measure model by Tone and Tsutsui [44], the ratio-form system efficiency model by Chen [45], the ratio-form process efficiency model (Chen et al [36], Cook et al [41]), the game theoretic model by Du et al [46] and the value-based model by Wei and Chang [47]. Besides, Kao [40] differentiated five types of the internal structure of the network DEA model, including the basic two-stage structure, the general two-stage structure, the series structure, the parallel structure, and the dynamic structure.…”