From d556186c7529796a12f4233272ecf9ad914ebe7f Mon Sep 17 00:00:00 2001
From: Peter Munch <peterrmuench@gmail.com>
Date: Sun, 5 Sep 2021 11:22:51 +0200
Subject: [PATCH] Extend references of HangingNodes

---
 doc/doxygen/references.bib                    | 19 +++++++++++++++++++
 .../matrix_free/hanging_nodes_internal.h      | 14 ++++++--------
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/doc/doxygen/references.bib b/doc/doxygen/references.bib
index 2696b6e2e2..b425869a1d 100644
--- a/doc/doxygen/references.bib
+++ b/doc/doxygen/references.bib
@@ -1459,3 +1459,22 @@
   pages =     {159--168},
   url =       {https://doi.org/10.1145/1837853.1693476}
 }
+
+@inproceedings{ljungkvist2017matrix,
+  title={Matrix-free finite-element computations on graphics processors with adaptively refined unstructured meshes.},
+  author={Ljungkvist, Karl},
+  booktitle={SpringSim (HPC)},
+  pages={1--1},
+  year={2017}
+}
+
+@article{kronbichler2019multigrid,
+  title={Multigrid for matrix-free high-order finite element computations on graphics processors},
+  author={Kronbichler, Martin and Ljungkvist, Karl},
+  journal={ACM Transactions on Parallel Computing (TOPC)},
+  volume={6},
+  number={1},
+  pages={1--32},
+  year={2019},
+  publisher={ACM New York, NY, USA}
+}
diff --git a/include/deal.II/matrix_free/hanging_nodes_internal.h b/include/deal.II/matrix_free/hanging_nodes_internal.h
index 225b654d04..f13aee5beb 100644
--- a/include/deal.II/matrix_free/hanging_nodes_internal.h
+++ b/include/deal.II/matrix_free/hanging_nodes_internal.h
@@ -138,10 +138,9 @@ namespace internal
     /**
      * This class creates the mask used in the treatment of hanging nodes in
      * CUDAWrappers::MatrixFree.
-     * The implementation of this class is explained in <em>Section 3 of
-     * Matrix-Free Finite-Element Computations On Graphics Processors With
-     * Adaptively Refined Unstructured Meshes</em> by Karl Ljungkvist,
-     * SpringSim-HPC, 2017 April 23-26.
+     * The implementation of this class is explained in Section 3 of
+     * @cite ljungkvist2017matrix and in Section 3.4 of
+     * @cite kronbichler2019multigrid.
      */
     template <int dim>
     class HangingNodes
@@ -1141,10 +1140,9 @@ namespace CUDAWrappers
     /**
      * This function resolves the hanging nodes using tensor product.
      *
-     * The implementation of this class is explained in <em>Matrix-Free
-     * Finite-Element Computations On Graphics Processors With Adaptively
-     * Refined Unstructured Meshes</em> by Karl Ljungkvist, SpringSim-HPC, 2017
-     * April 23-26.
+     * The implementation of this class is explained in Section 3 of
+     * @cite ljungkvist2017matrix and in Section 3.4 of
+     * @cite kronbichler2019multigrid.
      */
     template <int dim, int fe_degree, bool transpose, typename Number>
     __device__ void
-- 
2.39.5