1. “Conservation” below age three: fact or artifact?;Achenbach,1969
2. Learning and operational convergence in logical thought development;Beilin;Journal of Experimental Child Psychology,1965
3. Cognitive capacities of young children: a replication;Beilin;Science,1968
4. Stimulus and cognitive transformation in conservation;Beilin,1969
5. The training and acquisition of logical operations;Beilin,1971