J. Bruce Tomblin, Nancy L. Records, Paula Buckwalter, Xuyang Zhang, Elaine Smith, Marlea O’Brien,
Prevalence of Specific Language Impairment in Kindergarten Children Journal of Speech Language and Hearing Research. ,vol. 40, pp. 1245- 1260 ,(1997) ,
10.1044/JSLHR.4006.1245