Facilitating two-word utterances in two Down's syndrome boys.
D002675:Child, Preschool; D004314:Down Syndrome; D004495:Education of Persons with Intellectual Disabilities; D005793:Generalization, Psychological; D006801:Humans; D007100:Imitative Behavior; D007223:Infant; D007802:Language; D007804:Language Development; D008297:Male; D010988:Play and Playthings; D012054:Reinforcement, Psychology; D014825:Vocabulary