1. The Quality of Life Research Center, Teglgårdstræde 4-8, DK-1452 Copenhagen K, Denmark
2. Norwegian School of Management, Sandvika, Norway
3. National Institute of Child Health and Human Development, Office of the Medical Director, Division for Mental Retardation, Ministry of Social Affairs, Jerusalem and Zusman Child Development Center, Division of Pediatrics and Community Health, Ben Gurion University, Beer-Sheva, Israel