Areal activities and stratification of hydrolytic enzymes involved in the biochemical cycles of carbon, nitrogen, sulphur and phosphorus in podsolized boreal forest soils. - Wittmann,C..; Kahkonen,M..A..; Ilvesniemi,H..; Kurola,J..; Salkinoja-Salonen,M..S.. (Soil Biology and Biochemistry, 2004)