Norms for four standard developmental milestones by sex, social class and place in family.
D002657:Child Development; D002675:Child, Preschool; D005190:Family; D005260:Female; D006801:Humans; D007223:Infant; D007804:Language Development; D008297:Male; D009043:Motor Activity; D012737:Sex Factors; D012923:Social Class; D013060:Speech