diff --git a/Alpha_shapes_3/demo/Alpha_shapes_3/Alpha_shape_3.cpp b/Alpha_shapes_3/demo/Alpha_shapes_3/Alpha_shape_3.cpp
index e3e606a974c..c5607761dad 100644
--- a/Alpha_shapes_3/demo/Alpha_shapes_3/Alpha_shape_3.cpp
+++ b/Alpha_shapes_3/demo/Alpha_shapes_3/Alpha_shape_3.cpp
@@ -16,7 +16,7 @@ int main(int argc, char** argv)
   application.setAttribute(Qt::AA_UseDesktopOpenGL);
 
   // Import resources from libCGALQt (Qt5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
 
   CGAL_QT_INIT_RESOURCES;
   Q_INIT_RESOURCE(Alpha_shape_3);
diff --git a/GraphicsView/demo/Alpha_shapes_2/Alpha_shapes_2.cpp b/GraphicsView/demo/Alpha_shapes_2/Alpha_shapes_2.cpp
index b740e3c096e..4d85393bbdc 100644
--- a/GraphicsView/demo/Alpha_shapes_2/Alpha_shapes_2.cpp
+++ b/GraphicsView/demo/Alpha_shapes_2/Alpha_shapes_2.cpp
@@ -186,7 +186,7 @@ void MainWindow::alphaChanged(int i)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
diff --git a/GraphicsView/demo/Apollonius_graph_2/Apollonius_graph_2.cpp b/GraphicsView/demo/Apollonius_graph_2/Apollonius_graph_2.cpp
index 2ddacd7e80d..06b6664a0d2 100644
--- a/GraphicsView/demo/Apollonius_graph_2/Apollonius_graph_2.cpp
+++ b/GraphicsView/demo/Apollonius_graph_2/Apollonius_graph_2.cpp
@@ -151,7 +151,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
@@ -284,7 +284,7 @@ int main(int argc, char **argv)
   app.setApplicationName("Apollonius_graph_2 demo");
 
   // Import resources from libCGAL (Qt5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_QT_INIT_RESOURCES;
   Q_INIT_RESOURCE(Apollonius_graph_2);
 
diff --git a/GraphicsView/demo/Bounding_volumes/Bounding_volumes.cpp b/GraphicsView/demo/Bounding_volumes/Bounding_volumes.cpp
index 0e4cf2daba6..884029f3b5d 100644
--- a/GraphicsView/demo/Bounding_volumes/Bounding_volumes.cpp
+++ b/GraphicsView/demo/Bounding_volumes/Bounding_volumes.cpp
@@ -350,7 +350,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
@@ -541,7 +541,7 @@ int main(int argc, char **argv)
   app.setApplicationName("Bounding_volumes demo");
 
   // Import resources from libCGAL (Qt5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_QT_INIT_RESOURCES;
 
   MainWindow mainWindow;
diff --git a/GraphicsView/demo/Circular_kernel_2/Circular_kernel_2.cpp b/GraphicsView/demo/Circular_kernel_2/Circular_kernel_2.cpp
index f49e7b85cc7..8ccfb5b7316 100644
--- a/GraphicsView/demo/Circular_kernel_2/Circular_kernel_2.cpp
+++ b/GraphicsView/demo/Circular_kernel_2/Circular_kernel_2.cpp
@@ -181,7 +181,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
diff --git a/GraphicsView/demo/Generator/Generator_2.cpp b/GraphicsView/demo/Generator/Generator_2.cpp
index ec1b55ff4a0..586c9033f7a 100644
--- a/GraphicsView/demo/Generator/Generator_2.cpp
+++ b/GraphicsView/demo/Generator/Generator_2.cpp
@@ -172,7 +172,7 @@ MainWindow::MainWindow()
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
@@ -339,7 +339,7 @@ int main(int argc, char **argv)
   app.setApplicationName("Generator_2 demo");
 
   // Import resources from libCGAL (Qt5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_QT_INIT_RESOURCES;
   Q_INIT_RESOURCE(Generator_2);
 
diff --git a/GraphicsView/demo/L1_Voronoi_diagram_2/L1_voronoi_diagram_2.cpp b/GraphicsView/demo/L1_Voronoi_diagram_2/L1_voronoi_diagram_2.cpp
index f4218dd6101..ce35c9fc222 100644
--- a/GraphicsView/demo/L1_Voronoi_diagram_2/L1_voronoi_diagram_2.cpp
+++ b/GraphicsView/demo/L1_Voronoi_diagram_2/L1_voronoi_diagram_2.cpp
@@ -213,7 +213,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
diff --git a/GraphicsView/demo/Largest_empty_rect_2/Largest_empty_rectangle_2.cpp b/GraphicsView/demo/Largest_empty_rect_2/Largest_empty_rectangle_2.cpp
index b2bfdc6c5b3..2657ab97707 100644
--- a/GraphicsView/demo/Largest_empty_rect_2/Largest_empty_rectangle_2.cpp
+++ b/GraphicsView/demo/Largest_empty_rect_2/Largest_empty_rectangle_2.cpp
@@ -185,7 +185,7 @@ MainWindow::MainWindow()
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
@@ -278,7 +278,7 @@ int main(int argc, char **argv)
   app.setApplicationName("Largest_empty_rectangle_2 demo");
 
   // Import resources from libCGAL (Qt5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_QT_INIT_RESOURCES;
   Q_INIT_RESOURCE(Largest_empty_rectangle_2);
 
diff --git a/GraphicsView/demo/Periodic_2_triangulation_2/Periodic_2_Delaunay_triangulation_2.cpp b/GraphicsView/demo/Periodic_2_triangulation_2/Periodic_2_Delaunay_triangulation_2.cpp
index 5e344f0df0a..191c7f20181 100644
--- a/GraphicsView/demo/Periodic_2_triangulation_2/Periodic_2_Delaunay_triangulation_2.cpp
+++ b/GraphicsView/demo/Periodic_2_triangulation_2/Periodic_2_Delaunay_triangulation_2.cpp
@@ -216,7 +216,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
@@ -444,7 +444,7 @@ int main(int argc, char **argv)
   app.setApplicationName("Periodic_2_Delaunay_triangulation_2 demo");
 
   // Import resources from libCGAL (Qt5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_QT_INIT_RESOURCES;
 
   MainWindow mainWindow;
diff --git a/GraphicsView/demo/Polygon/Polygon_2.cpp b/GraphicsView/demo/Polygon/Polygon_2.cpp
index 2f0535cdc30..5a505d8fa2b 100644
--- a/GraphicsView/demo/Polygon/Polygon_2.cpp
+++ b/GraphicsView/demo/Polygon/Polygon_2.cpp
@@ -206,7 +206,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
@@ -573,7 +573,7 @@ int main(int argc, char **argv)
   app.setApplicationName("Polygon_2 demo");
 
   // Import resources from libCGAL (Qt5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_QT_INIT_RESOURCES;
   Q_INIT_RESOURCE(Polygon_2);
 
diff --git a/GraphicsView/demo/Segment_Delaunay_graph_2/Segment_voronoi_2.cpp b/GraphicsView/demo/Segment_Delaunay_graph_2/Segment_voronoi_2.cpp
index 4edb2a88876..e6ccd1859e8 100644
--- a/GraphicsView/demo/Segment_Delaunay_graph_2/Segment_voronoi_2.cpp
+++ b/GraphicsView/demo/Segment_Delaunay_graph_2/Segment_voronoi_2.cpp
@@ -212,7 +212,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
diff --git a/GraphicsView/demo/Snap_rounding_2/Snap_rounding_2.cpp b/GraphicsView/demo/Snap_rounding_2/Snap_rounding_2.cpp
index 077fa2680c5..9e46f805c4a 100644
--- a/GraphicsView/demo/Snap_rounding_2/Snap_rounding_2.cpp
+++ b/GraphicsView/demo/Snap_rounding_2/Snap_rounding_2.cpp
@@ -198,7 +198,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
@@ -307,7 +307,7 @@ int main(int argc, char **argv)
   app.setApplicationName("Snap_rounding_2 demo");
 
   // Import resources from libCGAL (Qt5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_QT_INIT_RESOURCES;
   Q_INIT_RESOURCE(Snap_rounding_2);
 
diff --git a/GraphicsView/demo/Spatial_searching_2/Spatial_searching_2.cpp b/GraphicsView/demo/Spatial_searching_2/Spatial_searching_2.cpp
index bf43bee1209..b5ed84b1500 100644
--- a/GraphicsView/demo/Spatial_searching_2/Spatial_searching_2.cpp
+++ b/GraphicsView/demo/Spatial_searching_2/Spatial_searching_2.cpp
@@ -188,7 +188,7 @@ void MainWindow::N_changed(int i)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
@@ -291,7 +291,7 @@ int main(int argc, char **argv)
   app.setApplicationName("Spatial_searching_2 demo");
 
   // Import resources from libCGAL (Qt5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_QT_INIT_RESOURCES;
   Q_INIT_RESOURCE(Spatial_searching_2);
 
diff --git a/GraphicsView/demo/Stream_lines_2/Stream_lines_2.cpp b/GraphicsView/demo/Stream_lines_2/Stream_lines_2.cpp
index 91330dd947d..b84e4f79aa4 100644
--- a/GraphicsView/demo/Stream_lines_2/Stream_lines_2.cpp
+++ b/GraphicsView/demo/Stream_lines_2/Stream_lines_2.cpp
@@ -122,7 +122,7 @@ MainWindow::MainWindow()
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
@@ -240,7 +240,7 @@ int main(int argc, char **argv)
   app.setApplicationName("Stream_lines_2 demo");
 
   // Import resources from libCGAL (Qt5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_QT_INIT_RESOURCES;
   Q_INIT_RESOURCE(Stream_lines_2);
 
diff --git a/GraphicsView/demo/Triangulation_2/Constrained_Delaunay_triangulation_2.cpp b/GraphicsView/demo/Triangulation_2/Constrained_Delaunay_triangulation_2.cpp
index 676e17795a8..51163bbe1bd 100644
--- a/GraphicsView/demo/Triangulation_2/Constrained_Delaunay_triangulation_2.cpp
+++ b/GraphicsView/demo/Triangulation_2/Constrained_Delaunay_triangulation_2.cpp
@@ -371,7 +371,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
diff --git a/GraphicsView/demo/Triangulation_2/Delaunay_triangulation_2.cpp b/GraphicsView/demo/Triangulation_2/Delaunay_triangulation_2.cpp
index 2ae9a885386..8f7ec1fe5ce 100644
--- a/GraphicsView/demo/Triangulation_2/Delaunay_triangulation_2.cpp
+++ b/GraphicsView/demo/Triangulation_2/Delaunay_triangulation_2.cpp
@@ -197,7 +197,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
diff --git a/GraphicsView/demo/Triangulation_2/Regular_triangulation_2.cpp b/GraphicsView/demo/Triangulation_2/Regular_triangulation_2.cpp
index 66051932c0d..b67399a1649 100644
--- a/GraphicsView/demo/Triangulation_2/Regular_triangulation_2.cpp
+++ b/GraphicsView/demo/Triangulation_2/Regular_triangulation_2.cpp
@@ -168,7 +168,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
diff --git a/GraphicsView/doc/GraphicsView/GraphicsView.txt b/GraphicsView/doc/GraphicsView/GraphicsView.txt
index d5f15a926a3..000358aea14 100644
--- a/GraphicsView/doc/GraphicsView/GraphicsView.txt
+++ b/GraphicsView/doc/GraphicsView/GraphicsView.txt
@@ -8,17 +8,17 @@ namespace CGAL {
 \cgalAutoToc
 \authors Andreas Fabri and Laurent Rineau
 
-<A HREF="http://qt-project.org/doc/qt-4.8/">Qt</A> is a <span class="textsc">Gui</span> toolkit for
+<A HREF="http://qt-project.org/doc/qt-5/">Qt</A> is a <span class="textsc">Gui</span> toolkit for
 cross-platform application development.
 
 \section GraphicsViewIntroduction Introduction
 
 This chapter describes classes that help to visualize two dimensional \cgal objects
-with the <A HREF="http://qt-project.org/doc/qt-4.8/graphicsview.html">Qt Graphics View Framework</A>.
+with the <A HREF="http://qt-project.org/doc/qt-5/graphicsview.html">Qt Graphics View Framework</A>.
 
-This framework uses the model view paradigm. <A HREF="http://qt-project.org/doc/qt-4.8/qgraphicsitem.html">`QGraphicsItem`</A>s are stored in a 
-<A HREF="http://qt-project.org/doc/qt-4.8/qgraphicsscene.html">`QGraphicsScene`</A> 
-and are displayed in a <A HREF="http://qt-project.org/doc/qt-4.8/qgraphicsview.html">`QGraphicsView`</A>. The items 
+This framework uses the model view paradigm. <A HREF="http://qt-project.org/doc/qt-5/qgraphicsitem.html">`QGraphicsItem`</A>s are stored in a 
+<A HREF="http://qt-project.org/doc/qt-5/qgraphicsscene.html">`QGraphicsScene`</A> 
+and are displayed in a <A HREF="http://qt-project.org/doc/qt-5/qgraphicsview.html">`QGraphicsView`</A>. The items 
 have a paint method which is called when an item is in the visible area of a view.
 The framework is also responsible for dispatching events from the view
 via the scene to the items. The framework is extensible in the sense
@@ -50,14 +50,14 @@ classes that have to override member functions adhering to this naming scheme.
 \section GraphicsViewOverall Overall Design
 
 In \cgalFigureRef{graphicsviewuml} you see four classes depicted in grey,
-that come from the %Qt Graphics View Framework. The <A HREF="http://qt-project.org/doc/qt-4.8/qgraphicsscene.html">`QGraphicsScene`</A>
-contains <A HREF="http://qt-project.org/doc/qt-4.8/qgraphicsitem.html">`QGraphicsItem`</A>s, which get displayed in any number
-of <A HREF="http://qt-project.org/doc/qt-4.8/qgraphicsview.html">`QGraphicsView`</A>s. The views are widgets, that is they take screen space
+that come from the %Qt Graphics View Framework. The <A HREF="http://qt-project.org/doc/qt-5/qgraphicsscene.html">`QGraphicsScene`</A>
+contains <A HREF="http://qt-project.org/doc/qt-5/qgraphicsitem.html">`QGraphicsItem`</A>s, which get displayed in any number
+of <A HREF="http://qt-project.org/doc/qt-5/qgraphicsview.html">`QGraphicsView`</A>s. The views are widgets, that is they take screen space
 in an application.
 
-The fourth class is the <A HREF="http://qt-project.org/doc/qt-4.8/qobject.html">`QObject`</A>. It plays an important role in %Qt for
-event handling and memory management. First, it allows to add <A HREF="http://qt-project.org/doc/qt-4.8/signalsandslots.html">signals and
-slots</A>, and to connect them. Second, it allows to install <A HREF="http://qt-project.org/doc/qt-4.8/eventsandfilters.html">event filters</A>.
+The fourth class is the <A HREF="http://qt-project.org/doc/qt-5/qobject.html">`QObject`</A>. It plays an important role in %Qt for
+event handling and memory management. First, it allows to add <A HREF="http://qt-project.org/doc/qt-5/signalsandslots.html">signals and
+slots</A>, and to connect them. Second, it allows to install <A HREF="http://qt-project.org/doc/qt-5/eventsandfilters.html">event filters</A>.
 
 \cgalFigureBegin{graphicsviewuml,uml-design.png}
 UML Class Diagram with the %Qt classes (blue), \cgal classes for using the framework (yellow), \cgal data structures (red), and application classes (green).
@@ -68,8 +68,8 @@ UML Class Diagram with the %Qt classes (blue), \cgal classes for using the frame
 In order to visualize for example a `CGAL::Delaunay_triangulation_2`, we
 provide the graphics item class `CGAL::Qt::TriangulationGraphicsItem<T>`.
 It provides a `paint` method that draws the edges and vertices of a triangulation
-using the drawing primitives of the <A HREF="http://qt-project.org/doc/qt-4.8/qpainter.html">`QPainter`</A>. The color of vertices and edges, 
-can be chosen by setting a user defined <A HREF="http://qt-project.org/doc/qt-4.8/qpen.html">`QPen`</A>.
+using the drawing primitives of the <A HREF="http://qt-project.org/doc/qt-5/qpainter.html">`QPainter`</A>. The color of vertices and edges, 
+can be chosen by setting a user defined <A HREF="http://qt-project.org/doc/qt-5/qpen.html">`QPen`</A>.
 
 As this graphics item only stores a pointer to a triangulation, it
 must be notified about changes like the insertion of points coming from
diff --git a/GraphicsView/doc/GraphicsView/PackageDescription.txt b/GraphicsView/doc/GraphicsView/PackageDescription.txt
index 495f4b59b0d..1ff546cadc3 100644
--- a/GraphicsView/doc/GraphicsView/PackageDescription.txt
+++ b/GraphicsView/doc/GraphicsView/PackageDescription.txt
@@ -13,7 +13,7 @@
 \cgalPkgPicture{detail.png}
 \cgalPkgSummaryBegin
 \cgalPkgAuthors{Andreas Fabri and Laurent Rineau}
-\cgalPkgDesc{This package provides classes for displaying \cgal objects  and data structures in the <A HREF="http://qt-project.org/doc/qt-4.8/graphicsview.html">Qt 4 Graphics View Framework</A>.}
+\cgalPkgDesc{This package provides classes for displaying \cgal objects  and data structures in the <A HREF="http://qt-project.org/doc/qt-5/graphicsview.html">Qt 4 Graphics View Framework</A>.}
 \cgalPkgManuals{Chapter_CGAL_and_the_Qt_Graphics_View_Framework,PkgGraphicsView}
 \cgalPkgSummaryEnd
 \cgalPkgShortInfoBegin
@@ -26,7 +26,7 @@
 
 This package provides some classes which allow to use \cgal classes in
 <I>Qt</I> applications which make use of the <A
-HREF="http://qt-project.org/doc/qt-4.8/graphicsview.html">Qt Graphics
+HREF="http://qt-project.org/doc/qt-5/graphicsview.html">Qt Graphics
 View Framework</A>.
 
 \cgalClassifedRefPages
diff --git a/GraphicsView/package_info/GraphicsView/description.txt b/GraphicsView/package_info/GraphicsView/description.txt
index 1c4fbfdbdf5..f68f59045fb 100644
--- a/GraphicsView/package_info/GraphicsView/description.txt
+++ b/GraphicsView/package_info/GraphicsView/description.txt
@@ -1,3 +1,3 @@
 The future 2D graphics package using the GraphicsView framework
-http://doc.trolltech.com/4.3/graphicsview.html
+http://doc.qt.io/qt-5/graphicsview.html
 
diff --git a/Linear_cell_complex/demo/Linear_cell_complex/Linear_cell_complex_3_demo.cpp b/Linear_cell_complex/demo/Linear_cell_complex/Linear_cell_complex_3_demo.cpp
index 6825880e0ff..1dc662eb614 100644
--- a/Linear_cell_complex/demo/Linear_cell_complex/Linear_cell_complex_3_demo.cpp
+++ b/Linear_cell_complex/demo/Linear_cell_complex/Linear_cell_complex_3_demo.cpp
@@ -38,7 +38,7 @@ int main(int argc, char** argv)
   application.setApplicationName("3D Linear Cell Complex");
 
   // Import resources from libCGALQt5
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_Qt_init_resources();// that function is in a DLL
   Q_INIT_RESOURCE(Linear_cell_complex_3);
 
diff --git a/Mesh_3/demo/Mesh_3/Mesh_3.cpp b/Mesh_3/demo/Mesh_3/Mesh_3.cpp
index 5cded27dbb0..2387aef62ab 100644
--- a/Mesh_3/demo/Mesh_3/Mesh_3.cpp
+++ b/Mesh_3/demo/Mesh_3/Mesh_3.cpp
@@ -12,7 +12,7 @@ int main(int argc, char **argv)
   app.setApplicationName("Mesh_3 demo");
 
   // Import resources from libCGALQt ( Qt5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_QT_INIT_RESOURCES;
 
   MainWindow mainWindow;
diff --git a/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Periodic_Lloyd_3.cpp b/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Periodic_Lloyd_3.cpp
index 058f9767978..ce0dfc38e3b 100644
--- a/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Periodic_Lloyd_3.cpp
+++ b/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/Periodic_Lloyd_3.cpp
@@ -11,7 +11,7 @@ int main(int argc, char** argv)
   application.setApplicationName("3D Periodic Lloyd");
 
   // Import resources from libCGAL (QT5).
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
   CGAL_QT_INIT_RESOURCES;
   Q_INIT_RESOURCE(Periodic_Lloyd_3);
 
diff --git a/Polyhedron/demo/Polyhedron/Polyhedron_demo_mesh_3_plugin_cgal_code.cpp b/Polyhedron/demo/Polyhedron/Polyhedron_demo_mesh_3_plugin_cgal_code.cpp
index b081a5796f9..032839022bf 100644
--- a/Polyhedron/demo/Polyhedron/Polyhedron_demo_mesh_3_plugin_cgal_code.cpp
+++ b/Polyhedron/demo/Polyhedron/Polyhedron_demo_mesh_3_plugin_cgal_code.cpp
@@ -354,7 +354,7 @@ public:
         QMenu* menu = Scene_item::contextMenu();
 
         // Use dynamic properties:
-        // http://doc.trolltech.com/lastest/qobject.html#property
+        // http://doc.qt.io/qt-5/qobject.html#property
         bool menuChanged = menu->property(prop_name).toBool();
 
         if(!menuChanged) {
diff --git a/Polyhedron/demo/Polyhedron/Scene_combinatorial_map_item.cpp b/Polyhedron/demo/Polyhedron/Scene_combinatorial_map_item.cpp
index 2bdab9f72c6..3707db422c7 100644
--- a/Polyhedron/demo/Polyhedron/Scene_combinatorial_map_item.cpp
+++ b/Polyhedron/demo/Polyhedron/Scene_combinatorial_map_item.cpp
@@ -268,7 +268,7 @@ QMenu* Scene_combinatorial_map_item::contextMenu()
     QMenu* menu = Scene_item::contextMenu();
 
     // Use dynamic properties:
-    // http://doc.trolltech.com/lastest/qobject.html#property
+    // http://doc.qt.io/qt-5/qobject.html#property
     bool menuChanged = menu->property(prop_name).toBool();
 
     if(!menuChanged) {
diff --git a/Polyhedron/demo/Polyhedron/Scene_points_with_normal_item.cpp b/Polyhedron/demo/Polyhedron/Scene_points_with_normal_item.cpp
index b2db6046702..ca2c93bc663 100644
--- a/Polyhedron/demo/Polyhedron/Scene_points_with_normal_item.cpp
+++ b/Polyhedron/demo/Polyhedron/Scene_points_with_normal_item.cpp
@@ -678,7 +678,7 @@ QMenu* Scene_points_with_normal_item::contextMenu()
     QMenu* menu = Scene_item::contextMenu();
 
     // Use dynamic properties:
-    // http://doc.trolltech.com/lastest/qobject.html#property
+    // http://doc.qt.io/qt-5/qobject.html#property
     bool menuChanged = menu->property(prop_name).toBool();
 
     if(!menuChanged) {
diff --git a/Polyhedron/demo/Polyhedron/Scene_polyhedron_item.cpp b/Polyhedron/demo/Polyhedron/Scene_polyhedron_item.cpp
index 1d94841e769..33bdf7264cf 100644
--- a/Polyhedron/demo/Polyhedron/Scene_polyhedron_item.cpp
+++ b/Polyhedron/demo/Polyhedron/Scene_polyhedron_item.cpp
@@ -816,7 +816,7 @@ QMenu* Scene_polyhedron_item::contextMenu()
     QMenu* menu = Scene_item::contextMenu();
 
     // Use dynamic properties:
-    // http://doc.trolltech.com/lastest/qobject.html#property
+    // http://doc.qt.io/qt-5/qobject.html#property
     bool menuChanged = menu->property(prop_name).toBool();
 
     if(!menuChanged) {
diff --git a/Polyhedron/demo/Polyhedron/Scene_polylines_item.cpp b/Polyhedron/demo/Polyhedron/Scene_polylines_item.cpp
index 1a36c543265..7c447d88a62 100644
--- a/Polyhedron/demo/Polyhedron/Scene_polylines_item.cpp
+++ b/Polyhedron/demo/Polyhedron/Scene_polylines_item.cpp
@@ -721,7 +721,7 @@ QMenu* Scene_polylines_item::contextMenu()
     QMenu* menu = Scene_item::contextMenu();
 
     // Use dynamic properties:
-    // http://doc.trolltech.com/lastest/qobject.html#property
+    // http://doc.qt.io/qt-5/qobject.html#property
     bool menuChanged = menu->property(prop_name).toBool();
 
     if(!menuChanged) {
diff --git a/Polyline_simplification_2/demo/Polyline_simplification_2/Polyline_simplification_2.cpp b/Polyline_simplification_2/demo/Polyline_simplification_2/Polyline_simplification_2.cpp
index 9b4e7952885..1d33978803b 100644
--- a/Polyline_simplification_2/demo/Polyline_simplification_2/Polyline_simplification_2.cpp
+++ b/Polyline_simplification_2/demo/Polyline_simplification_2/Polyline_simplification_2.cpp
@@ -247,7 +247,7 @@ MainWindow::processInput(CGAL::Object o)
 
 /* 
  *  Qt Automatic Connections
- *  http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+ *  http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
  * 
  *  setupUi(this) generates connections to the slots named
  *  "on_<action_name>_<signal_name>"
diff --git a/Principal_component_analysis/demo/Principal_component_analysis/PCA_demo.cpp b/Principal_component_analysis/demo/Principal_component_analysis/PCA_demo.cpp
index 1fcd919e233..eac8974765b 100644
--- a/Principal_component_analysis/demo/Principal_component_analysis/PCA_demo.cpp
+++ b/Principal_component_analysis/demo/Principal_component_analysis/PCA_demo.cpp
@@ -35,7 +35,7 @@ int main(int argc, char **argv)
   app.setApplicationName("PCA demo");
 
   // Import resources from libCGALQt.
-  // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE
+  // See http://doc.qt.io/qt-5/qdir.html#Q_INIT_RESOURCE
 
   CGAL_QT_INIT_RESOURCES;
 
diff --git a/Triangulation_3/demo/Triangulation_3/MainWindow.cpp b/Triangulation_3/demo/Triangulation_3/MainWindow.cpp
index e49011b7f1d..54f47ad2c9c 100644
--- a/Triangulation_3/demo/Triangulation_3/MainWindow.cpp
+++ b/Triangulation_3/demo/Triangulation_3/MainWindow.cpp
@@ -7,7 +7,7 @@ MainWindow::MainWindow(QWidget* parent)
  : CGAL::Qt::DemosMainWindow(parent)
 {
   //  Qt Automatic Connections
-  //   http://doc.trolltech.com/4.4/designer-using-a-component.html#automatic-connections
+  //   http://doc.qt.io/qt-5/designer-using-a-ui-file.html#automatic-connections
   //  setupUi(this) automatically generates connections to the slots named
   //   "on_<action_name>_<signal_name>"
   setupUi(this);