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Non-convex Technologies and Cost Functions: Definitions, Duality and Nonparametric Tests of Convexity (Journal of Economics 81(2):155–192)
Briec, Walter, (2006)
Returns to Scale on Nonparametric Deterministic Technologies: Simplifying Goodness-of-Fit Methods Using Operations on Technologies
Briec, Walter, (2000)
A new criterion for technical efficiency measures: non-monotonicity across dimensions axioms
Kerstens, Kristiaan, (1999)