1. P. Exner, “An isoperimetric problem for point interactions,” J. Phys. A: Math. Gen., A38, 4795–4802 (2005).
2. G. Giorgadze and G. Khimshiashvili, “Concyclic and aligned equilibrium configurations of point charges,” Proc. I. Vekua Inst. Appl. Math., 67, 20–33 (2017).
3. G. Khimshiashvili, “Equilibria of constrained point charges,” Bull. Georgian Natl. Acad. Sci., 7, No. 2, 15–20 (2013).
4. G. Khimshiashvili, “Equilibria of point charges on elastic contour,” Bull. Georgian Natl. Acad. Sci., 11, No. 4, 7–12 (2017).
5. G. Khimshiashvili, G. Panina, and D. Siersma, “Equilibria of three constrained point charges,” J. Geom. Phys., 98, No. 2, 110–117 (2015).