Primary transitional objects.
D000367:Age Factors; D002657:Child Development; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009769:Object Attachment; D011574:Psychoanalytic Theory; D012903:Smell; D013391:Sucking Behavior; D014110:Touch