TY  - BOOK
AU  - Vahervuo,Toivo
TI  - Pupils' Arithmetical Ability : : Differences Due to the Teacher. A methodological Approach
T2  - Annales Academiae Scientiarum Fennicae. Ser. B. ; 
PY  - 1957///
CY  - Helsinki : 
PB  - Suomalainen Tiedeakatemia, 
ER  -