1. Webster's Unabridged Dictionary, Springfield, Mass., G.& C. Merriam Co.
2. Speech Defects and Related Oral Anomalies;Greene;J. Am. Dent. A.,1937
3. The Correction of Defective Consonant Sounds;Nemoy,1937
4. Speech Handicapped School Children;Johnson, Wendell, and others,1948
5. Speech Handicapped School Children;Johnson, Wendell, and others,1948