Figure 7 illustrates the authors of references cited in highly cited papers (HCP) related to biochar. Once again, the figure demonstrates the presence of closely interconnected authors who frequently cite each other in these highly cited papers. Figure 8 provides a close up of the citation pattern, once again prominent complex relationship, with Yong Sik Ok and Dan Tsang being dominant in their citations. They are closely linked to Hailong Wang, Ali El Naggar, Deyi Hou, Shaheen Sabry, and Binoy Sarkar, Jorg Rinklebe, Scott X. Chang, as evidenced by the interconnecting lines in the figure.