Cazals, Catherine, Florens, Jean-Pierre, Rouzaud, Séverine and De Rycke, Marc (1997) Scale Economies and Natural Monopoly in the Postal Delivery: Comparison between Parametric and Non Parametric Specifications. In: Managing Change in the Postal and Delivery Industries Crew, Michael A. and Kleindorfer, Paul R. (eds.) Springer. Series “Topics in Regulatory Economics and Policy”, Vol. 25. Chapter 4. pp. 65-82. ISBN 978-1-4615-6321-1

Cremer, Helmuth, Grimaud, André and De Rycke, Marc (1997) Costs and Benefits of Universal Service Obligations in the Postal Sector. In: Managing Change in the Postal and Delivery Industries Crew, Michael A. and Kleindorfer, Paul R. (eds.) Springer. Series “Topics in Regulatory Economics and Policy”, Vol. 25. Chapter 2. pp. 22-41. ISBN 978-1-4615-6321-1