1. The optimal age to learn a foreign language;Asher;Modern Language Journal,1969
2. The New Mexico State University Spanish Speaking Master's Program;Beecher;TESOL Quarterly,1974
3. Handbook for TOEFL applicants;Educational Testing Service,1977
4. Manual, Michigan test of English language proficiency;English Language Institute,1962
5. Language background, age, and the order of acquisition of English structures;Fathman,1976