1. Basset, P., Amelot, A., Vaissiére, J., & Roubeau, B. (2001). Nasal airflow in french spontaneous speech. Journal of the International Phonetic Association, 31(1), 87–99.
2. Bates, D., Maechler, M., Bolker, B., & Walker, S. (2014). lme4: Linear mixed- effects models using eigen and s4 [Computer software manual]. Retrieved Jan 2020 from http://CRAN.R-project.org/package=lme4
3. Beddor, P. (2015). The relation between language users’ perception and production repertoires. In Proceedings of the 18th international congress of phonetic sciences (icphs iixx, glasgow).
4. Davidson, L. (2006). Comparing tongue shapes from ultrasound imaging using smoothing spline analysis of variance. Journal of the Acoustical Association of America, 120(1), 407–415.
5. Davies, T. (1979). Schlieren photography: A tool for speech research. Acoustics Letters, 3, 73–75.