KOLEVA, Vanya, KOYNOVA, Teodora, DRAGOEVA, Asya, KOLEV, Nikolay, KULEVA, Ivayla and NATCHEV, Nikolay. Benefits for visitors provided by protected areas in Bulgaria and willingness to become a conservation volunteer. Ecological Questions. Online. 5 December 2023. Vol. 35, no. 2, pp. 59-65. [Accessed 6 July 2025]. DOI 10.12775/EQ.2024.016.