Tzonev, Rossen, Marius Dimitrov, Chavdar Gussev, Vladimir Vulchev, in Ivailo Nikolov. „Classificaton of the Relict Forest Communites of Palla’s Black Pine (Pinus Nigra Subsp. Pallasiana) in Bulgaria“. Hacquetia 17, no. 2 (julij 13, 2018). Pridobljeno april 7, 2025. https://ojs.zrc-sazu.si/hacquetia/article/view/6958.