1. Special education in Nigeria;Adesina,1989
2. Aitchison, J. (1996). The Language Webb: The 1996 Reith Lectures BBC Radio 4. London.
3. Service delivery systems and communication disorders in developing countries;Akpati,1986
4. American Speech-Language-Hearing Association. (1993). Definitions of communication disorders and Variations ASHA 35 (Suppl. 10), 40–1.
5. Edinburgh articulation test;Anthony,1971