Kleiner, Yuri A., and Larissa N. Kaminskaya. “The Neutral Vowel and the Lndeterminate Phoneme (Sprachbund Typology)”. Respectus Philologicus, no. 8 (13) (December 28, 2005): 97–103. Accessed August 28, 2026. https://journals.vu.lt/respectus-philologicus/article/view/37658.