1. Carpenter, T. P., Hiebert, J. and Moser, J. M.: 1981, ?Problem structure and first-grade children's initial solution processes for simple addition and subtraction problems?, Journal for Research in Mathematics Education 12, 27?39.
2. Carpenter, T. P. and Moser, J. M.: 1981, ?The development of addition and subtraction problem solving skills?, in T. P.Carpenter, J. M.Moser and T.Romberg (eds.) Addition and Subtraction, Lawrence Erlbaum Associates, Hillsdale, NJ.
3. Fischer, J. P.: 1979, ?L'enfant et le comptage?, IREM, Strasbourg, a paraitre.
4. Greeno, J. G.: 1980a, ?Some examples of cognitive task analysis with instructional implications?, in R. E.Snow, P.Federico and W. E.Montague (eds.), Aptitude, Learning, and Instruction, Vol. 2, Lawrence Erlbaum Associates, Hillsdale, NJ.
5. Greeno, J. G.: 1980b, ?Development of processes for understanding problems?, paper presented at Heidelberg Conference, Germany.