1. US Department of Energy, Multi year program plan 2007–2012. 2005, Published by the office of the biomass accessible at: http://www1.eere.energy.gov/biomass/pdfs/mypp.pdf
2. Envirochem Services, Identifying environmentally preferable uses for biomass resources, Prepared for Natural Resources Canada, Commission for Environmental Co-operation, National Research Council of Canada, 2004, accessible at: http://www.cec.org/files/PDF/ECONOMY/Biomass-Stage-I-II_en.pdf
3. Commission of the European communities (2005): Communication from the commission: Biomass action plan. 2005, accessible at http://ec.europa.eu/energy/res/biomass_action_plan/doc/2005_12_07_comm_biomass_action_plan_en.pdf
4. H. Bick, Grundzüge der Ökologie, Gustav Fischer-Verlag, Stuttgart 1993.
5. VCI Verband der chemischen Industrie 2001, quoted in R. Busch und J. Thoen, Lecture at Biorefinica, Osnabrück (Germany) 2004.