1. Alfsen, K. H. (1991a), ‘Some Comments on OECD's Preliminary Set of Environmental Indicators’, Mimeo, Central Bureau of Statistics, Oslo.
2. Alfsen, K. H. (1991b), ‘Some Comments on a Report on Canada's Progress Towards a National Set of Environmental Indicators’, Mimeo, Central Bureau of Statistics, Oslo.
3. Alfsen, K. H. (1991c), ‘Environmental Indicators of Denmark’, Mimeo, Central Bureau of Statistics, Oslo.
4. Discussion Paper;K. H. Alfsen,1992
5. ECE (1985), ‘Draft Set of ECE Environmental Indicators’, CES/548/Add.6/Rev.1.