Eilbeck, JC, “Quasiperiodic and periodic solutions for vector nonlinear Schrodinger equations”, Journal of Mathematical Physics, 41:12 (2000), 8236
Christiansen, PL, “Quasi-periodic and periodic solutions for coupled nonlinear Schrodinger equations of Manakov type”, Proceedings of the Royal Society of London Series A-Mathematical Physical and Engineering Sciences, 456:2001 (2000), 2263