TY  - GEN
AU  - Piaget,Jean
TI  - The child's conception of number / 
SN  - 710031424
U1  - 155 
PY  - 1941///
CY  - London: 
PB  - Routledge and Kegan Paul Ltd., 
KW  - Child psychology
KW  - Number concept
KW  - Number concept in children
KW  - Cognition in children
KW  - Childerens
ER  -