1. ACTFL. (2013). ACTFL reading proficiency test (RPT). Familiarization manual and ACTFL proficiency guidelines 2012—reading. Retrieved on July 2 2020 fromhttps://www.languagetesting.com/pub/media/wysiwyg/manuals/ACTFL_FamManual_Reading_2019.pdf
2. ACTFL. (2014). ACTFL listening proficiency test (LPT). Familiarization manual and ACTFL proficiency guidelines 2012—listening. Retrieved on July 2 2020 fromhttps://www.languagetesting.com/pub/media/wysiwyg/manuals/ACTFL_FamManual_Listening_2019.pdf
3. Sampling Bias and the Problem of Generalizability in Applied Linguistics
4. Current Trends in Online Language Learning
5. Measuring oral proficiency in distance, face‐to‐face, and blended classrooms;Blake R. J.;Language Learning & Technology,2008