1. Four unifying ideas behind primary mathematics;Bishop;Primary Mathematics,1968
2. “Streaming: Two Years Later”;Ferri,1971
3. “The Child's Understanding of Number”;Gelman,1978
4. “Taxonomy of Educational Objectives. Book 1 Cognitive Domain”;Bloom,1972
5. “Ability Grouping: The Banbury Enquiry”;Newbold,1977