1. Alban, D. H. 1974. Red pinc site index in Minnesota as related to soil and foliar nutrients. For. Sci. 20: 261?269.
2. Beadle, N. C. W. 1954. Soil phosphate and the delimination of plant communities in eastern Australia. Ecology 35: 370?375.
3. Binkley, D. & Hart, S. C. 1989. The components of nitrogen availability assessments in forest soils. Adv. Soil Sci. 10: 67?113.
4. Bradshaw, A. D. 1965. Evolutionary significance of phenotypic plasticity in plants. Adv. Genet. 13: 115?155.
5. Bradshaw, A. D. 1984. Ecological significance of genetic variation between populations. In: Dirzo, R. & Saruklan, J. (eds.). Perspectives on Plant Population Ecology, pp. 213?241. Sinauer Associates Inc. Publishers. Massachusetts.