Sabev, Sabi, Konstantin Chukalov, and Valeri Bakardzhiev. “DESIGNING A LABORATORY STAND FOR TESTING IMPACT RESISTANCE OF PLASTIC FILMS BY FREE-FALLING DART DROP ACCORDING ASTM D1709”. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference 3 (June 22, 2024): 268–273. Accessed November 23, 2024. https://journals.ru.lv/index.php/ETR/article/view/8139.