Krogh, L. “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 - Danish Journal of Geography, vol. 90, Jan. 1990, https://tidsskrift.dk/geografisktidsskrift/article/view/44816.