References
- Butler N. R., Peckham C. S., Sheridan M. D. Speech Defects in Children aged seven years. B.M.J. 1973; 1: 253
- Renfrew C. E. Action Picture Test, C. E. Renfrew. North Place, Old Headington, Oxford 1968
- Van Riper C. Predictive Screening Test of Articulation. Western Michigan University, Kalamazoo 1968