TY  - BOOK
AU  - Opalvh,Robert Edward
TI  - The role of complexity in Piaget's object permanent tasts
PY  - 1979///
CY  - Ann Arbor, Mich.
PB  - University Microfilms International
KW  - Piaget, Jean, 1896
N1  - Thesis (Ph.D.) - University of California, 1978
ER  -