Alakukku, L., A. Ristolainen, I. Sarikka, and T. Hurme. “Surface Water Ponding on Clayey Soils Managed by Conventional and Conservation Tillage in Boreal Conditions”. Agricultural and Food Science, vol. 19, no. 4, Jan. 2010, pp. 313-26, doi:10.2137/145960610794197551.