Frederiksen, Peter. 1985. “Strategies and Designs for Afforestation, Reforestation and Tree Planting: Proceedings of an International Symposium on the Occasion of 100 Years of Forestry Education and Research in the Netherlands, Wageningen, 19-23 September 1983. Ed.: K. F. Wiersum”. Geografisk Tidsskrift 85 (januar). https://tidsskrift.dk/geografisktidsskrift/article/view/44165.