Krogh, L. (1989) “Acidic precipitation: proceedings of the International Symposium on Acidic Precipitation, Muskoka, Ontario, September 15-20, Ed. by Hans C. Martin. (Water, air, and soil vol. 30-31”, Geografisk Tidsskrift, 89. Tilgængelig hos: https://tidsskrift.dk/geografisktidsskrift/article/view/44754 (Set: 7marts2021).