1. Euler, L., Considerationes de motu corporum coelestium, Novi commentarii academiae scientiarum Petropolitanae, 1764, vol. 10, pp. 544–558 (read at Berlin in April 1762). See also: Opera Omnia, s.2, vol. 25, pp. 246–257, with corrections and comments by M. Schũrer.
2. Lũtzen, J., Joseph Liouville, 1809–1882, Master of Pure and Applied Mathematics, New York: Springer-Verlag, 1990, p. 653.
3. Mayer, A.M., Floating Magnets, Nature, 1878, vols. 17 and 18, pp. 487–488 and 258–260.
4. Aref, H., On the Equilibrium and Stability of a Row of Point Vortices, J. Fluid Mech., 1995, vol. 290, pp. 167–181.
5. Aref, H., Newton, P.K., Stremler, M.A., Tokieda, T. and Vainchtein, D.L., Vortex Crystals, Adv. Appl. Mech., 2003, vol. 39, pp. 1–79.