1. Blasius D et al. 1989 Agric. Ecosystems Environ. 28, 27–30.
2. Gerant D et al. 1987 In Relationships between Above and Belowground Influences of Air Pollutants on Forest Trees. Eds. J Bervaes, P Mathy and P Evers. EUR 11738EN, CEC Proceeding, Wageningen 15–17 Dec. 1987. pp 109–118.
3. Gower S T et al. 1992 Ecol. Monogr. 62, 43–65.
4. Joslin J D and Henderson G S 1984 Forest Sci. 30, 965–970.
5. Lassheikki M et al. 1991 Scand. J. For. Res. 6, 91–104.