Chen, Xiaoci, Zhanglu Tan, and Siwen Li. “Study on the Characteristics of International Coal Trade on Complex Network”. Journal of Business Economics and Management 23, no. 4 (July 13, 2022): 797–817. Accessed October 5, 2024. https://ijspm.vgtu.lt/index.php/JBEM/article/view/15670.