%0 Journal Article
%A H.-P. Schr�cker 
%T Double Tangent Circles and Focal Properties of Sphero-Conics
%J Journal for geometry and graphics
%D 2008
%P 161-169
%V 12
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/JGG_2008_12_2_JGG_2008_12_2_a4/
%F JGG_2008_12_2_JGG_2008_12_2_a4