Tsouli, D., and B. Elabbadi. “Intellectual Capital Assessment Models in Clusters: A Literature Review”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 36, no. 6, Nov. 2017, pp. 18-26, https://www.gssrr.org/index.php/JournalOfBasicAndApplied/article/view/8360.