Roug-Hellichius, L. (1998). Babble, grunts and words: A study of phonetic shape and functional use in the beginnings of language. Dept. of Linguistics, University of Stockholm.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Roug-Hellichius, Liselotte. Babble, Grunts and Words: A Study of Phonetic Shape and Functional Use in the Beginnings of Language. Stockholm: Dept. of Linguistics, University of Stockholm, 1998.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Roug-Hellichius, Liselotte. Babble, Grunts and Words: A Study of Phonetic Shape and Functional Use in the Beginnings of Language. Dept. of Linguistics, University of Stockholm, 1998.
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