  In this work we consider the identifiability of two coefficients $a(u)$ and
$c(x)$ in a quasilinear elliptic partial differential equation from observation
of the Dirichlet-to-Neumann map. We use a linearization procedure due to Isakov
[On uniqueness in inverse problems for semilinear parabolic equations. Archive
for Rational Mechanics and Analysis, 1993] and special singular solutions to
first determine $a(0)$ and $c(x)$ for $x \in \Omega$. Based on this partial
result, we are then able to determine $a(u)$ for $u \in \mathbb{R}$ by an
adjoint approach.
