Mistrić, Davor, Leonard Eleršek, and Ernest Bazijanac. “Examination of Applicability of Engine Condition Trend Monitoring to Bell 2068 Ill Helicopter”. Promet - Traffic&Transportation 14, no. 1 (January 25, 2002): 23–27. Accessed August 26, 2025. https://traffic2.fpz.hr/index.php/PROMTT/article/view/1977.