5Gardner, R. Lalonde, MacPherson. Social Factors in Second Language Attrtion [ J ]. Langauge Learning 1985,55 (4) : 519 -540.
6Ecke P. Language Attrition and Theories of Forgetting: A Cross-disciplinary Review [ J ]. International Journal of Bilingualism ,2004,8 (3) : 321 - 354.
7Neisser, Ulric. Interpreting Harry Bahrick' s Discovery: What Confers Immunity Against Forgetting? [ J ]. Journal of Experimental Psychology: General, 1984, 113 (3) :32 -35.
8Bahrick H. Fifty Years of Second Language Attrition: Implications for Programmatic Research [ J ]. Modem Language Journl,1984,(68) : 105 - 118.
9Yoshitomi A. Towards a model of language attrition: Neurobiological and phychological contributions [ J ]. Issues in Applied Linguistics, 1992,3 (2) : 319 - 340.
10Smith M T. Tracking verb usage in adult speakers of Spanish as a second language : An attrition study. M. A. thesis. Brigham Young University, Provo, Utah, 1996.