TY  - BOOK
AU  - Stern,Catherine
AU  - Lehr,Marguerite
ED  - Harrap 
TI  - Children discover arithmetic: an introduction to structural arithmetic 
U1  - 372.72 23
PY  - 1953///.
CY  - London: 
PB  - George G. Harrap, 
KW  - Arithmetic
KW  - Study and teaching
N1  - Includes bibliography (p. 291-292)
ER  -