1. G P Agrawal, Nonlinear fibre optics, 6th Edn (Academic Press, New York, 2019)
2. A Hasegawa and Y Kodama, Solitons in optical communications (Oxford University Press, Oxford, 1995)
3. A Hasegawa and M Matsumoto, Optical solitons in fibres (Springer, New York, 2002)
4. S Roy, S K Bhadra and G P Agrawal, Opt. Commun. 282, 3798 (2009)
5. P K A Wai, C R Menyuk, Y C Lee and H H Chen, Opt. Lett. 11, 464 (1986)