5SIMAK M. A method for removal of filled dead seeds from a sample of Pinus contorta [J]. Seed Sci Technol, 1984, 12: 767 - 775.
6SALEN K, BERGSTEN U, WIKLUND K. Determination of viable and dead Scots pine seeds of different anatomical maturity after freezing using the IDX method [J]. Seed Sci Technol, 1995, 23:405 -414.