Zebec, Sabina, Ratko Zelenika, and Slobodan Zečević. “Measuring the Intellectual Capital of International Carriers As Logistic Operators”. Promet - Traffic&Transportation 19, no. 2 (March 25, 2007): 103–114. Accessed August 26, 2025. https://traffic2.fpz.hr/index.php/PROMTT/article/view/2214.