V. N. Kharin ,   L. V. Vetchinnikova ,   E. N. Spektor ,   Z. D. Bumagina Factor Analysis of Interrelations between Karelian Birch Curley Forms in the Hybrid Progeny in Karelia. Proceedings of the Sixth International Conference. Minsk. Vol. 1 , p. 197-202 , 01.2001