@ARTICLE{Cl03, author = {Clarenz, U.}, title = {A Stability Criterion for Extremals of Elliptic Parametric Functionals}, journal = {Pacific Journal of Mathematics}, year = {2003}, volume = {208}, pages = {231--242}, number = {2}, abstract = {In this paper we consider parametric integrals $\mathcal{F} $ with elliptic integrands depending on the surface normal. The main result is a stability criterion for $\mathcal{F} $-extremal immersions, containing the result of Barbosa and do Carmo \cite{badoca1} as a special case. Using similar techniques we are also able to show a condition for instability. The last section contains a simple proof of the fact that the surface normal of $\mathcal{F}$-extremals is topologically equivalent to a holomorphic function.}, pdf = {http://numod.ins.uni-bonn.de/research/papers/public/Cl03.pdf} }