Tzonev, R., M. Dimitrov, C. Gussev, V. Vulchev, and I. Nikolov. “Classificaton of the Relict Forest Communites of Palla’s Black Pine (Pinus Nigra Subsp. Pallasiana) in Bulgaria”. Hacquetia, vol. 17, no. 2, July 2018, https://ojs.zrc-sazu.si/hacquetia/article/view/6958.