1. 2) Shigo, A.L., Hillis, W.E.: Heartwood, discolored wood, and microorganisms in living trees. Ann. Rev. Phytopathology 11, 197-222 (1973) .
2. 3) Bamber, R.K., Fukazawa, K.: Sapwood and heartwood: a review. For. Abst. 46 (9) , 567-580 (1985).
3. 4) Hillis, W.E.: “Heartwood and tree exudates”, Springer Verlag, Berlin, etc., 1987.
4. 5) Magel, E.A.: Biochemistry and physiology of heartwood formation. “Cell and Molecular Biology of Wood Formation”, Savidge, R.A., Barnett, J.R., Napier, R. ed., BIOS Scientific Publishers, Oxford, 2000, pp.363-376.
5. 6) Taylor, A.M., Gartner, B.L., Morrell, J.J.: Heartwood formation and natural durability-a review. Wood and Fiber Sci. 34 (4) , 587-611 (2002).