1. The optimal age to gain a foreign language;Asher;Mod. Lang. J.,1969
2. Adults versus children in second language learning: psychological consideration;Ausubel;Mod. Lang. J.,1964
3. Contributions of psychological theory and educational research to the teaching of foreign language;Carroll;Mod. Lang. J.,1965
4. The foreign language attainments of language majors in the senior year: a survey conducted in U.S. colleges and universities;Carroll,1967
5. Language development;Ervin,1966