TY  - BOOK
AU  - Merttens, Ruth
TI  - Adding and subtracting: activities on addition, subtraction, measure and money 
SN  - 1-85270-010-6
AV  - TR(GS 513.2 MER 1987
PY  - 1987///
CY  - [s.l.]
PB  - Octopus pub. Group
KW  - Addition -- study and teaching
KW  - Subtraction -- study and teaching
ER  -