Clark Kimberling, Bicentric pair of points
and related triangle centers,
Forum Geometricorum, 3 (2003) 35--47.
Abstract: Bicentric pairs of points in the plane
of triangle ABC occur in connection with three configurations: (1) cevian
traces of a triangle center; (2) points of intersection of a central line
and central circumconic; and (3) vertex-products of bicentric triangles.
These bicentric pairs are formulated using trilinear coordinates. Various
binary operations, when applied to bicentric pairs, yield triangle centers.