TY  - BOOK
AU  - Sigel,Irving E.
AU  - Hooper,Frank H.joint comp
AU  - Piaget,Jean
TI  - Logical thinking in children; research based on Piaget's theory
PY  - 1968///
CY  - New York
PB  - Rinehart and Winston
KW  - Piaget, Jean, 1896
KW  - Conservation of substance (Psychology)
KW  - Child psychology
N1  - Includes bibliographies
ER  -