M. Hauke-Kowalska, E. Borowiak, W. Barzdajn, W. Kowalkwski, R. Korzeniewicz, and T. Wawro, “Cone and seeds variability in seed orchards and seed stands of Pinus sylvestris L. ”, BALT FOR, vol. 25, no. 2, pp. 187–192, Dec. 2019.