L. Brady, P. Xenitidis, “Systems of difference equations, symmetries, and integrability conditions”, TMF, 224:2 (2025), 257–275; Theoret. and Math. Phys., 224:2 (2025), 1324–1339
A. V. Mikhailov, J. P. Wang, P. Xenitidis, “Recursion operators, conservation laws, and integrability conditions for difference equations”, TMF, 167:1 (2011), 23–49; Theoret. and Math. Phys., 167:1 (2011), 421–443