TY  - BOOK
AU  - Carpenter,Thomas P.
AU  - Romberg,Thomas A.
AU  - Moser,James M.
TI  - Addition and subtraction: a cognitive perspective 
SN  - 0898591716
PY  - 1982///
CY  - Hillsdale, N. J.
PB  - Lawrence Erlbaum Associates
KW  - Addition
KW  - Subtraction
KW  - Mathematical ability
KW  - Testing
ER  -