9Synnestvedt M B, Chen C, Holmes J H. CiteSpace II: visualization and knowledge discovery in bibliographic databases. AMIA Annu Symp Proc. 2005:724-728.
10Chen C. Searching for intellectual turning points : progres -sive knowledge domain visualization.. Proc Natl Acad Sci U SA, 2004, 101(11): 5303-5310.