1. Introduction;Acton;RAND Journal of Economics,1989
2. Adato Energia, 2002. Electricity and district heating in 2001 (cited 13.1.2003 access available from http://www.energia.fi).
3. Adato Energia, 2003. Energia-alan taloustilasto (Economic statistics of the energy brance) 1990–1998 (received 03.09.2003 Email from risto.helio@energia.fi).
4. Modified regulation of telecommunications and public interest standard;Baumol,1995
5. Berg, S.V., Tschirhart, J., 1988. Natural Monopoly Regulation. Principles and Practice. Cambridge Surveys of Economic Literature. Cambridge University Press, Cambridge.