TY  - BOOK
AU  - x, x
AU  - Berger,Emil J.
TI  - Instructional aids in mathematics ; thirty-fourth yearbook: x
SN  - x    
U1  - Ref. 510.7/INS  
PY  - 1973///
CY  - Washington 
PB  - National Council of Teachers of Mathematics
KW  - Mathematics - Study and Teaching
KW  - National Council of Teachers of Mathematics
ER  -