9Collier,V.P.How long? A synthesis of research on academic achievement in a second language[J].TESOL Quarterly,23(3):509-531.
10David P.Dolson,Jan Mayer,Longitudinal Study of Three Program Models for Language-Minortity Students:A critical Examination of reported Findings[J].Bilingual Research Journal,16:1 & 2,Winter/Spring,1992:105-120.