Gradziuk, Piotr. “Economic Efficiency of Photovoltaic Installations (A Case Study at the Zwierzyniec–Biały Słup Research and Education Centre of Roztocze National Park)”. Regional Barometer. Analyses & Prognoses 12, no. 4 (February 23, 2015): 117–122. Accessed November 8, 2024. https://czaz.akademiazamojska.edu.pl/index.php/br/article/view/989.