Let ,
,
and
be the vertices of the outer Soddy triangle, and
also let ,
,
and
be the pairwise contact points of the three tangent circles. Then the lines , , and concur at a point known as the first Eppstein point (Kimberling), denoted by Eppstein (2001). Although Eppstein (2001) actually cited
(Oldknow 1996), he missed the fact that is equivalent to the inner Oldknow point defined by Oldknow
(1996).

Danneels, E. "The Eppstein Centers and the Kenmotu Points." Forum Geom.5, 173-180, 2005. http://forumgeom.fau.edu/FG2005volume5/FG200523index.html.Eppstein,
D. "Tangent Spheres and Triangle Centers." Amer. Math. Monthly108,
63-66, 2001.Kimberling, C. "Encyclopedia of Triangle Centers: X(481)=1st
Eppstein Point." http://faculty.evansville.edu/ck6/encyclopedia/ETC.html#X481.Oldknow,
A. "The Euler-Gergonne-Soddy Triangle of a Triangle." Amer. Math. Monthly103,
319-329, 1996.