message: reference formatting
diff: @@ -249,8 +249,8 @@ public:
  * If @a a is > 0, the filtering algorithm for the velocity field after every
  * time step from [1] is used.
  *
  - * [1] Paul Fischer, Julia Mullen: Filter-based stabilization of spectral
  - * element methods
  + * [1] Paul Fischer, Julia Mullen (2001) Filter-based stabilization of
  + * spectral element methods
  */
  void SetFilterAlpha(double a) { filter_alpha = a; }
  