TY - Generic T1 - The effects of air-borne ammonium sulphate on Pinus nigra in the Netherlands Y1 - 1985 A1 - Roelofs, J.G.M. A1 - Kempers, A.J. A1 - Houdijk, A.L.F.M. A1 - Jansen, J. JF - Plant Soil VL - 42 ER -