step-51: fix cite command

diff --git a/examples/step-51/doc/intro.dox b/examples/step-51/doc/intro.dox
index 68e71d234ed28fcd849a8854e3d16df8370b6a72..501ee4124c93c6901c3615aafc487907d55a7d09 100644 (file)
--- a/examples/step-51/doc/intro.dox
+++ b/examples/step-51/doc/intro.dox
@@ -30,7 +30,7 @@ for systems of equations in 2 or 3 dimensions.
 To alleviate the computational cost of solving such large linear systems,
 the hybridizable discontinuous Galerkin (HDG) methodology was introduced
 by Cockburn and co-workers
-(see the references in the recent HDG overview article by N.C. Nguyen and J. Peraire @cite{Ngu2012}).
+(see the references in the recent HDG overview article by N.C. Nguyen and J. Peraire @cite Ngu2012).
 The HDG method achieves
 this goal by formulating the mathematical problem using Dirichlet-to-Neumann
 mappings.  The partial differential equations are first written as a first