4Ohniwa R L, Hibino A, Takeyasu K. Trends in Research Foci in Life Science Fields over the Last 30 Years Monitored by Emerging Topics[J]. Scientometrics, 2010, 85 ( 1 ) : 111 - 127.
5Janssens F, Leta J, Glanzel W, et al. Towards Mapping Library and Irfformation Science [ J ]. Information Processing & Management,2006, 42(6) :1614 - 1642.
6Sardinha, Andrew P B. Applications of WordSmith Keywords[ J]. Liverpool Working Papers in Applied Linguistics, 1996, 2( 1 ) : 81 - 90.
7Donohue J C. Understanding Scientific Literatures-A Bibliometric Approach[M]. Cambridge: The MIT Press,1973 : 49 - 50.
8Bamgbose, A.(1987), "When is Language Planning not Planning?" in Journal of West African Languages, 17 (1), pp.6-14.
9Bamgbose, A.(1991), Language and the Nation: The Language Question in Sub - Saharan Africa. Edinburgh: Edinburgh University Press for International African Institute.
10Chumbow, B.A.(1987), "Towards a Language Planning Model for Africa", in Journal of West African Languages, 17 (1), pp. 15-22.