TY  - BOOK
AU  - Swain,Robert L.
TI  - Understanding arithmetic
AV  - QA142 .S9
U1  - 511 
PY  - 1957///]
CY  - New York
PB  - Rinehart
KW  - Number concept
KW  - Local
KW  - Arithmetic
KW  - Study and teaching
KW  - Foundations
ER  -