1. Addoms, R. M.: Nutritional studies on Loblolly Pine. Plant Physiol. 12, 199 (1937).
2. Ashby, W. R.: Introduction to cybernetics. London: Chapman and Hall 1956.
3. Bakuzis, E. V.: Forest Synecology. (Lecture notes) School of Forestry, University of Minnesota 1968.
4. Barnes, R. L.: The study of mineral requirements of excised tree roots, pp. 39–45. In: Mineral nutrition of trees. Duke University, School of Forestry Bull. 15 (1959).
5. Barrows, H. L.: Evaluating the micronutrient requirements of trees, pp. 18–31. In: Mineral nutrition of trees. Duke University, School of Forestry Bull. 15 (1959).