Scharinger, Mathias Max Planck Research Group Auditory Cognition, MPI for Human Cognitive and Brain Sciences, Max Planck Society; Department of Linguistics, University of Maryland, College Park, MD, USA;
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3956075/ (Any fulltext)
Scharinger, M., & Idsardi, W. (2014). Sparseness of vowel category structure: Evidence from English dialect comparison. Lingua, 140, 35-51. doi:10.1016/j.lingua.2013.11.007.