REFERENCES
(1) Ministry of Trade and Industry. Finland and Energy.
(2) Hokkanen, Veikko P.S. Cogen.and DH-The Solution for Energy Economy and a Cleaner Environ.in Helsinki.
(3) Helsinki Energy. Helsinki-The Energy Efficient City
(4) Helsinki Energy. Energy for Helsinki.
(5) Finnish District Heating Association (FDHA). District Heating From Finland.
(6) Helsinki Energy. Appendix to the Annual Report of 1995.
(7) Energy Board of Helsinki-City of Helsinki. Helsinki Utility Tunnels.