1. 2012 ACTFL performance descriptors for language learners 2012 edition
2. 2017 America's Languages: Investing in language education for the 21st century https://www.amacad.org/multimedia/pdfs/publications/researchpapersmonographs/language/Commission-on-Language-Learning_Americas-Languages.pdf
3. 2017 https://d3itqxtdxl1nz0.cloudfront.net/pdfs/STAMP-National-Averages-Update-2017.pdf
4. Brecht , R. D. Davidson , D. E. Ginsberg , R. B. 1993 NFLC occasional papers
5. Partner-language learning trajectories in dual-language immersion: Evidence from an urban district;Burkhauser;Foreign Language Annals,2016