TY  - JOUR
AU  - Fr. Fabricius-Bjerre
TI  - A relation between the numbers of singular points and singular lines of a plane closed curve.
JO  - Mathematica Scandinavica
PY  - 1977
SP  - 20
EP  - 24
VL  - 40
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MS2_1977__40_166511/
ID  - MS2_1977__40_166511
ER  -