Working paper Delivery Offices Cost Frontier: a Robust Non Parametric Approach with Exogenous Variables Catherine Cazals, Paul Dudley, Jean-Pierre Florens, S. Patel, and Frank Rodriguez IDEI Working Paper n. 406, 2006 ReferenceCatherine Cazals, Paul Dudley, Jean-Pierre Florens, S. Patel, and Frank Rodriguez, “Delivery Offices Cost Frontier: a Robust Non Parametric Approach with Exogenous Variables”, IDEI Working Paper, n. 406, 2006.