I have an exercise to linearize the following nonlinear system

$$\dot{x} = A - B x - x y^2$$
$$\dot{y} = A\cdot (x y^2 - y)$$

I tried it with

    osz = NonlinearStateSpaceModel[{{A - B*x - x*y^2, A*(x*y^2 - y)}, {x, y}}, {x, y}, {A, B}]

for the input of this system. 

 How can I linearize this system now? 

`StateTransformationLinearize[osz]` 
doesnt obviously work, because its not an affine system...