Nadelman, L.,Begun, A.,M. Lamb,B. Sutton-Smith (Eds.)(1982).Sibling relationships: Their nature and significance across the lifespan.Hillsdalle, N.J.:Erlbaum.
Stewart, R. B.,Mobely, L. A.,VanTuyl, S. S.,Salvador, M. A.(1987).The firstborn`s adjustment to the birth of sibling: A longitudinal assessment.Child Development.58,341-355.