The humus of a "Parabraunerde" (Orthic Luvisol) under Fagus sylvatica L and Quercus robur L and its modification in 25 years L Beyer, HP Blume and U IrmlerAnn. For. Sci., 48 3 (1991) 267-278DOI: https://doi.org/10.1051/forest:19910303