TY  - JOUR
AU  - Stefanov, Simeon
AU  - Dragieva, Velika
TI  - Evolution of Sets Systems and Homotopy Groups of Spheres
JO  - Mathematics and Education in Mathematics
PY  - 2012
SP  - 202
EP  - 206
VL  - 41
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MEM_2012_41_1_a20/
LA  - en
ID  - MEM_2012_41_1_a20
ER  -