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2. Bergsten U., Removal of dead-filled seeds and invigoration of viable seeds: a review of a seed conditioning concept used on conifers in Sweden, in: Edwards D.G.W. (Ed.), Dormancy and Barriers to Germination, International Symposium IUFRO project group P2.04-00 (Seed problems); 1991, Forestry Canada, Pacific Forestry Centre, Victoria, British Columbia, 1993, pp. 7-15.