1Chen, C.Searching for intellectual turning points: Progres- sive Knowledge Domain Visualization. Proc. Nat. Acad. Sci, 2004, 101:5303-5310.
2Chen,C.CiteSpace If: Detecting and visualizing emerging trends and transient patterns in scientific literature. Journal of the American Society for Information Science and Technology, 2006,57(3): 359-377.
