TY  - BOOK
AU  - Freudenthal, Hans.
TI  - Didactical Phenomenology of Mathematical Structures / 
SN  - 90-277-1535-1
U1  - B(T:3) 
CY  - BAoston : 
PB  - D.Reidel Publishing Company.
KW  - Mathematics <Natural Numbers>
ER  -