@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 1}
}