  We consider a general anisotropic massive SU(N) fermionic model, and
investigate its quantum integrability. In particular, by regularizing singular
operator products, we derive a system of equations resulting in the S-matrix
and find some non-trivial solutions. We illustrate our findings on the example
of a SU(3) model, and show that the Yang-Baxter equation is satisfied in the
massless limit for all coupling constants, while in the massive case the
solutions are parameterized in terms of the exceptional solutions to the
eight-vertex model.
