TY  - GEN
AU  - Vergnaud, Gerard
TI  - Classification of cognitive tasks and operations of thought involved in addition and subtraction problems
KW  - Psicologia Educacional
KW  - 3500 - Psicologia Educacional
UR  - https://catalogo.ispa.pt/opac/biblioteca/localizacao_doc/e2.htm
ER  -