7Kopp R F, White E H, Abrahamson L P, et al. Willow biomass trials in central New York State [ J ]. Biomass and Bioenergy,1993,5(2) : 179-187.
8S G Larsson, Melin, Rosenqvist H. Commercial harvest of willow wood chips in Sweden [ C ]. Proceedings of the 10 th European Conference and Technology Exhibition, Biomass for Energy and Industry, Germany, 1998, 200-203.
9Christersson L,Sennerhy F. Willow and poplar research and plantation in Sweden to day [ J ]. Swedish University of Agricultural Sciences, 1995.
