Đurić, Branimir, Marijana Mošić, and Aleksandar Trifunović. “The Research on the Environmental Impact of Buses and Engines Powered by Compressed Natural Gas”. Put i saobraćaj 65, no. 1 (April 13, 2019): 43-49. Accessed May 24, 2019. http://putisaobracaj.rs/index.php/PiS/article/view/44.