Soderholm, P. (2000), ‘Environmental Regulations and Interfuel Substitution in the Power
Sector: A Generalized Leontief Model’, Energy and Environment, 11(1): 1–24.


and  


Soderholm, P. (1998), ‘The Modelling of Fuel Use in the Power Sector: A Survey of
Econometric Analyses’, The Journal of Energy Literature, IV(2): 3–27.

Thanks