ENH: surfaceLambdaMuSmooth: added reference

applications/utilities/surface/surfaceLambdaMuSmooth/surfaceLambdaMuSmooth.C

@@ -33,6 +33,9 @@ Description
     Provide an edgeMesh file containing points that are not to be moved during
     smoothing in order to preserve features.
 
+    lambda/mu smoothing: G. Taubin, IBM Research report Rc-19923 (02/01/95)
+    "A signal processing approach to fair surface design"
+
 \*---------------------------------------------------------------------------*/
 
 #include "argList.H"