V E Adler, R I Yamilov, “Explicit auto-transformations of integrable chains”, J. Phys. A: Math. Gen., 27, № 2, 1994, 477
Xing-Biao Hu, “Nonlinear superposition formulae for the differential-difference analogue of the KdV equation and two-dimensional Toda equation”, J. Phys. A: Math. Gen., 27, № 1, 1994, 201
S.I. Svinolupov, R.I. Yamilov, “The multi-field Schrödinger lattices”, Physics Letters A, 160, № 6, 1991, 548
I. T. Khabibullin, “Boundary conditions for nonlinear equations compatible with integrability”, Theor Math Phys, 96, № 1, 1993, 845