1. Baran, H., Krasil′shchik, I.S., Morozov, O.I., Vojčák, P.: Nonlocal symmetries of Lax integrable equations: a comparative study. Submitted to Theor. Math. Phys. (2016). arXiv:1611.04938
2. Ferapontov, E.V.: Surfaces in 3-space possessing nontrivial deformations which preserve the shape operator. In: Integrable Systems in Differential Geometry, Tokyo, July 2000, Contemporary Mathematics, vol. 508, pp. 145–159. AMS, Providence (2002). arXiv:math/0107122
3. Gibbons, J., Tsarev, S.P.: Reductions of the Benney equations. Phys. Lett. A 211, 19–24 (1996)
4. Göktas, Ü., Hereman, W.: Symbolic computation of conserved densities for systems of nonlinear evolution equations. J. Symb. Comput. 24(5), 591–621 (1997)
5. Golovko, V.A., Kersten, P.H.M., Krasil′shchik, I.S., Verbovetsky, A.M.: On integrability of the Camassa-Holm equation and its invariants. Acta Appl. Math. 101, 59–83 (2008)