[en] It is shown that the two-dimensional (anti psipsi)2 model is, for N = 3, equivalent to the supersymmetric sine-Gordon equation, and for N = 4, equivalent to two decoupled sine-Gordon systems. In addition, it is argued that the kinks of this model are isospinors, and some of the higher conservation laws that are responsible for the exact solubility of this system are constructed. (Auth.)