Reference

G. Wingsle, M. Strand, S. Karpinski, J.-E. Hällgren (1992): Influence of SO2 and NO2 Expositure on Antioxidants and Photosynthesis in Needles of Pinus sylvestris. – Phyton, Annales Rei Botanicae, Horn – 32_3: 147 - 153.