1. Kummer, A.W.: Cleft Palate and Craniofacial Anomalies: Effects on Speech and Resonance (2007)
2. Peterson-Falzone, M. A. H.-J. S. J., Karnell, M.P.: Cleft palate speech (2001)
3. Grunwell, P., Sell, D.: Speech and cleft palate/velopharyngeal anomalies. Management of Cleft Lip and Palate. Whurr, London (2001)
4. Whitehill, T.: Assessing intelligibility in speakers with cleft palate: a critical review of the literature. Cleft Palate-Craniofacial Journal : Official Publication of the American Cleft Palate-craniofacial Association, vol. 39, pp. 50–8 (2002)
5. Zajac, D.J., Vallino, L.: Evaluation and management of cleft lip and palate: a developmental perspective (2017)