1. G. Abrahamsen, D. Drablos, and A. Tollan, 1980 . Acid precipitation, plant nutrients and forest growth . - In: ), Proc., Int. conf. ecol. impact acid precip. SNSF-project, Norway, pp.58 -63 .
2. G. Abrahamsen, K. Bjor, R. Horntvedt, B. Tveite, and F. H. Braekke, 1976 . Effects of acid precipitation on coniferous forest . - In: ), Impact of acid precipitation on forest and freshwater ecosystems in Norway. SNSF-project, FR 6/76, Oslo-As, pp.36 -63 .
3. G. Abrahamsen, K. Bjor, and O. Teigen, 1976 . Field experiments with simulated acid rain in forest ecosystems. I. Soil and vegetation characteristics, experimental design and equipment . SNSF-project, FR 4/76, Oslo-As, pp.1 -15 .