1. Feynman R, Leighton R, Sands M (1964) Feynman lectures on physics, vol II. Addison-Wesley, Boston
2. Delaunay B (1934) Sur la sphère vide. A la mémoire de Georges Voronoï. Bulletin de l’Academie des Sciences de l’URSS 7(6):793–800
3. Delone BN (1937) Geometry of positive quadratic forms. Uspekhi Matem Nauk 3:16–62 (in Russian)
4. Delone BN, Dolbilin NP, Stogrin MI, Galiuilin RV (1976) A local criterion for regularity of a system of points. Sov Math Dokl 17:319–322
5. Penrose R (1974) The role of aesthetics in pure and applied mathematical research. Bull Inst Math Appl 10:266