diff --git a/Periodic_4_hyperbolic_triangulation_2/demo/Periodic_4_hyperbolic_triangulation_2/include/internal/Qt/VoronoiGraphicsItem.h b/Periodic_4_hyperbolic_triangulation_2/demo/Periodic_4_hyperbolic_triangulation_2/include/internal/Qt/VoronoiGraphicsItem.h
index 2018cb7835c..cb5c0355570 100644
--- a/Periodic_4_hyperbolic_triangulation_2/demo/Periodic_4_hyperbolic_triangulation_2/include/internal/Qt/VoronoiGraphicsItem.h
+++ b/Periodic_4_hyperbolic_triangulation_2/demo/Periodic_4_hyperbolic_triangulation_2/include/internal/Qt/VoronoiGraphicsItem.h
@@ -15,7 +15,6 @@
 // $URL$
 // $Id$
 // SPDX-License-Identifier: GPL-3.0+
-// 
 //
 // Author(s)     : Andreas Fabri <Andreas.Fabri@geometryfactory.com>
 //                 Laurent Rineau <Laurent.Rineau@geometryfactory.com>
diff --git a/Periodic_4_hyperbolic_triangulation_2/demo/Periodic_4_hyperbolic_triangulation_2/include/internal/hyperbolic_free_motion_animation.h b/Periodic_4_hyperbolic_triangulation_2/demo/Periodic_4_hyperbolic_triangulation_2/include/internal/hyperbolic_free_motion_animation.h
index 5598144b0ff..14be062e2a9 100644
--- a/Periodic_4_hyperbolic_triangulation_2/demo/Periodic_4_hyperbolic_triangulation_2/include/internal/hyperbolic_free_motion_animation.h
+++ b/Periodic_4_hyperbolic_triangulation_2/demo/Periodic_4_hyperbolic_triangulation_2/include/internal/hyperbolic_free_motion_animation.h
@@ -3,7 +3,7 @@
 //
 // This file is part of CGAL (www.cgal.org).
 // You can redistribute it and/or modify it under the terms of the GNU
-// Interal Public License as published by the Free Software Foundation,
+// General Public License as published by the Free Software Foundation,
 // either version 3 of the License, or (at your option) any later version.
 //
 // Licensees holding a valid commercial license may use this file in
diff --git a/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Hyperbolic_octagon_translation.h b/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Hyperbolic_octagon_translation.h
index 0cb2e6efebc..30f05ea7ff3 100644
--- a/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Hyperbolic_octagon_translation.h
+++ b/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Hyperbolic_octagon_translation.h
@@ -3,7 +3,7 @@
 //
 // This file is part of CGAL (www.cgal.org).
 // You can redistribute it and/or modify it under the terms of the GNU
-// Interal Public License as published by the Free Software Foundation,
+// General Public License as published by the Free Software Foundation,
 // either version 3 of the License, or (at your option) any later version.
 //
 // Licensees holding a valid commercial license may use this file in
@@ -16,7 +16,6 @@
 // $Id$
 // SPDX-License-Identifier: GPL-3.0+
 //
-//
 // Author(s)     : Iordan Iordanov <iordan.iordanov@loria.fr>
 
 #ifndef CGAL_HYPERBOLIC_OCTAGON_TRANSLATION
diff --git a/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Periodic_4_hyperbolic_triangulation_2.h b/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Periodic_4_hyperbolic_triangulation_2.h
index 0661f3f7f65..9814b05e6b9 100644
--- a/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Periodic_4_hyperbolic_triangulation_2.h
+++ b/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Periodic_4_hyperbolic_triangulation_2.h
@@ -3,7 +3,7 @@
 //
 // This file is part of CGAL (www.cgal.org).
 // You can redistribute it and/or modify it under the terms of the GNU
-// Interal Public License as published by the Free Software Foundation,
+// General Public License as published by the Free Software Foundation,
 // either version 3 of the License, or (at your option) any later version.
 //
 // Licensees holding a valid commercial license may use this file in
diff --git a/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Periodic_4_hyperbolic_triangulation_face_base_2.h b/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Periodic_4_hyperbolic_triangulation_face_base_2.h
index 3120d66818c..783098bd4df 100644
--- a/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Periodic_4_hyperbolic_triangulation_face_base_2.h
+++ b/Periodic_4_hyperbolic_triangulation_2/include/CGAL/Periodic_4_hyperbolic_triangulation_face_base_2.h
@@ -14,7 +14,7 @@
 //
 // $URL$
 // $Id$
-//
+// SPDX-License-Identifier: GPL-3.0+
 //
 // Author(s)     : Iordan Iordanov  <Iordan.Iordanov@loria.fr>
 //
diff --git a/Periodic_4_hyperbolic_triangulation_2/include/CGAL/internal/Hyperbolic_octagon_translation_word.h b/Periodic_4_hyperbolic_triangulation_2/include/CGAL/internal/Hyperbolic_octagon_translation_word.h
index 4d25ee4eec0..7ebfbffd4f0 100644
--- a/Periodic_4_hyperbolic_triangulation_2/include/CGAL/internal/Hyperbolic_octagon_translation_word.h
+++ b/Periodic_4_hyperbolic_triangulation_2/include/CGAL/internal/Hyperbolic_octagon_translation_word.h
@@ -3,7 +3,7 @@
 //
 // This file is part of CGAL (www.cgal.org).
 // You can redistribute it and/or modify it under the terms of the GNU
-// Interal Public License as published by the Free Software Foundation,
+// General Public License as published by the Free Software Foundation,
 // either version 3 of the License, or (at your option) any later version.
 //
 // Licensees holding a valid commercial license may use this file in
@@ -14,7 +14,7 @@
 //
 // $URL$
 // $Id$
-//
+// SPDX-License-Identifier: GPL-3.0+
 //
 // Author(s)     : Iordan Iordanov <iordan.iordanov@loria.fr>