Zebec, Sabina, Ratko Zelenika, and Slobodan Zečević. “Measuring the Intellectual Capital of International Carriers As Logistic Operators”. Promet - Traffic&Transportation 19, no. 2 (1): 103-114. Accessed September 22, 2021. http://traffic.fpz.hr/index.php/PROMTT/article/view/941.