Briec W, K Kerstens and PV Eeckaut (2004). “Non-Convex Technologies and Cost Functions: Definitions, Duality and Nonparametric Tests of Convexity.” J Economics 81(2): 155-192.
Briec W, K Kerstens and PV Eeckaut (2004). “Non-Convex Technologies and Cost Functions: Definitions, Duality and Nonparametric Tests of Convexity.” J Economics 81(2): 155-192.