Garcia, Serge <https://www.idref.fr/05848924X>, Moreaux, Michel <https://www.idref.fr/031616623> and Reynaud, Arnaud <https://www.idref.fr/15826956X>  (2004) Measuring Economies of Vertical Integration in Network Industries: an Application to the Water Sector.  IDEI Working Paper, n. 255