1. Brown, G.N. (1978) Control of cold hardiness in tree shoots. In: Li, P.H. and Sakai, A. (eds.) Plant cold hardiness and freezing stress, pp. 297–304. Academic Press, New York.
2. Channel, M.G.R. and Shephard, L.J. (1982) Seasonal changes in the frost hardiness of provenances of Picea sitchensis in Scotland. Forestry 55: 137–153.
3. Day, W.R. and Peace, T.R. (1934) The experimental production and the diagnosis of frost injury on forest trees. Clarendon Press, Oxford. 60 p.
4. Glerum, C. (1973) Annual trend in frost hardiness and electrical impedance for seven coniferous species. Can. J. Plant Sei. 53: 881–889.
5. Glerum, C. and Farrar, J.L. (1966) Frost ring formation in the stems of some coniferous species. Can. J. Bot. 44: 879–886.