3[14]Kazuto Matsumura Ed.,1998.Studies in Endangered Languages,Paper from the International Symposium on Endangered Languages[J],Tokyo,November 18~20,1995 Japan.
4[15]Lenore A.Grenoble and Lindsay J.Whaley Ed.,1998.Endangered Languages,Current issues and future prospects[M],Cambridge University Press UK.
5[16]UNESCO Ad Hoc Expert Group on Endangered Languages.2003.Language Vitality and Endangerment,Document submitted to the International Expert Meeting on UNESCO Programmed Safeguarding of Endangered Languages[J],Paris,10~12 March 2003.