Maohua Li, Yinshan Guo, Jianwei Shi. “Hot Spots of OBE Concept Research in China in the Past 20 Years--Visual Analysis Based on CNKI”. Design Engineering, Vol. 2021, no. 04, May 2021, pp. 884 -88, http://thedesignengineering.com/index.php/DE/article/view/1475.