Volgen op een afstand 1975-1979 : Cognitieve ontwikkeling moeilijk lerenden

The study is concerned with the cognitive development of mentally retarded young persons. These persons are compared with a control group, including a replication after three...本研究聚焦于智力障碍青年（mentally retarded young persons）的认知发展（cognitive development）。研究将该群体与对照组（control group）进行对比，并包含三次后的重复实验（replication），原文内容未完整。