8Baumol, W J, (1977) , "On the Proper Cost Tests for Natural Monopoly in a Multi-product Industry" , American Economic Review, 67, pp. 809-822.
9Baumol, W J, Panzar, J C and R D Willig (1982) ,Contestable Market and the Theory of Industry Structure, Harcourt Brace Jovanovich.
10Economldes, N and White, L J. (1994) , "Networks and Compatibility: Implications for Antitrust" , European Economic Review, 38 (Maroh) , pp. 651-662.
