1. A. D.Aleksandrov, Convex polyhedra (Russian). Gosud. Izdat. Techniko-Teoretičeskoj Literatury, Moskwa 1950.
2. Z. Dziechcińska-Halamoda andA. Lasoń, Some properties of the centre of a convex set in the plane (Polish). Zesz. Nauk. WSP Opole, Matematyka16, 53–60 (1973).
3. Z. Dziechcińska-Halamoda, Characterization of the set of centers of a convex body by support cones (Polish). Zesz. Nauk. WSP Opole, Matematyka21, 93–100 (1979).
4. Z. Dziechcińska-Halamoda, On centers of a Cartesian product of convex sets (Polish). Zesz. Nauk. WSP Opole, Matematyka22, 7–11 (1980).
5. B.Grünbaum, Measures of symmetry for convex sets. Proc. of Symp. in Pure Math. VII, Amer. Math. Soc. R.I. 233–270 (1963).