  In this paper we study existence and uniqueness of renormalized solution to
the following problem $\lambda (x,u) -div a(x,Du) +\Phi (x,u)) =f$ with $f$ in
$L^1$ and with Dirichlet-Neumann boundary condition. The main difficulty in
this task is that in general the operator entering in the above equation is not
coercive in a Sobolev space. Moreover, the possible degenerate character of
$\lambda$ with respect to $u$ renders more complex the proof of uniqueness for
integrable data $f$.
