Figure 3.

(A) The document co-citation network clustering. The nodes and links are distinguished by colors, in which cool-toned color refers to an earlier co-citation relationship. References with > 10 citations are displayed in the landscape in nodes named by first author (publication year). The size of the node represents the citation number. Nodes with red ring serve as the references with citation bursts meaning emergence of new trends. The links refer to the beginning of the connections. (B) The top 20 references with the strongest bursts. The red bar refers to the burst duration. The appearance of dark blue bar represents the publication of the article. The burst strength indicates the importance of this article to the research field.