TY  - JOUR
AU  - H.-P. Schr�cker 
TI  - Double Tangent Circles and Focal Properties of Sphero-Conics
JO  - Journal for geometry and graphics
PY  - 2008
SP  - 161
EP  - 169
VL  - 12
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/JGG_2008_12_2_JGG_2008_12_2_a4/
ID  - JGG_2008_12_2_JGG_2008_12_2_a4
ER  -