V.M. Buchstaber, S. Igonin, S. Konstantinou-Rizos, and M.M. Preobrazhenskaia, "Yang--Baxter maps, Darboux transformations, and linear approximations of refactorisation problems", J. Phys. A: Math. Theor. 53 (2020), 504002 https://doi.org/10.1088/1751-8121/abc72b