1. M J Ablowitz and H Segur, Solitons and the inv erse scattering transform (SIAM, Philadelphia, 1981)
2. T Dauxois and M Peyard, Physics of solitons (Cambridge University Press, Cambridge, 2006)
3. See, for instance, L Pitaevskii and S Stringari, Bose–Einstein condensation (Oxford University Press, Oxford, 2003), and references therein
4. S Burger et al, Phys. Rev . Lett. 83, 5198 (1999)
5. J Denschlag et al, Science 287, 97 (2000)