1. Oenema, O., Oudendag, D., Velthof, G.L.: Nutrient losses from manure management in the European Union. Livest. Sci. 112, 261–272 (2007)
2. Council Directive 91/676/EEC of 12 December 1991 concerning the protection of waters against pollution caused by nitrates from agricultural sources
3. Møller, H.B., Nielsen, A.M., Nakakubo, A., Olsen, H.J.: Process performance of biogas digesters incorporating pre-separated manure. Livest. Sci. 112, 217–223 (2007)
4. Triolo, J.M., Ward, A.J., Pedersen, L., Sommer, S.G.: Characteristics of animal slurry as a key biomass for biogas production in Denmark. In: Matovic, M.D. (ed.) Biomass Now—Sustainable Growth and Use, pp. 307–326. InTech, Croatia (2013)
5. Foged, H.L. (ed.): Technologies for handling of livestock manuren. Livestock Manure to Energy—Status, Technologies and Innovation in Denmark, pp.16–17. Agro Business Park A/S, Tjele (2012)