We present an integrability test for discrete equations on the square lattice, which is based on the existence of a generalized symmetry. We apply this test to a number of equations obtained in different recent papers. As a result we prove the integrability of seven equations which differ essentially from the QV equation introduced by Viallet and thus from the Adler-Bobenko-Suris list of equations contained therein.
Levi, D., Yamilov, R.i. (2011). Generalized symmetry integrability test for discrete equations on the square lattice. JOURNAL OF PHYSICS. A, MATHEMATICAL AND THEORETICAL, 44(14) [10.1088/1751-8113/44/14/145207].