diff --git a/Triangulation_3/doc_tex/Triangulation_3_ref/Delaunay_triangulation_3.tex b/Triangulation_3/doc_tex/Triangulation_3_ref/Delaunay_triangulation_3.tex
index 32562761a10..1ce51b1dfb7 100644
--- a/Triangulation_3/doc_tex/Triangulation_3_ref/Delaunay_triangulation_3.tex
+++ b/Triangulation_3/doc_tex/Triangulation_3_ref/Delaunay_triangulation_3.tex
@@ -65,7 +65,7 @@ construction of the Voronoi diagram:
 \ccConstructor{template < class InputIterator >
        Delaunay_triangulation_3 (InputIterator first, InputIterator last,
  const DelaunayTriangulationTraits_3& traits = DelaunayTriangulationTraits_3())}
-{Equivalent to contructing an empty triangulation with the optional 
+{Equivalent to constructing an empty triangulation with the optional 
 traits class argument and calling \ccc{insert(first,last)}.}
 
 \ccOperations
@@ -349,10 +349,6 @@ These methods are  mainly a debugging help for the users of advanced features.
 
 \ccSeeAlso
 
-\ccc{CGAL::Triangulation_hierarchy_3}.
-
-%% \ccExample
-
-%% \ccIncludeExampleCode{Triangulation3/Delaunay_triangulation_3_prog.cpp}
+\ccc{CGAL::Triangulation_hierarchy_3}
 
 \end{ccRefClass}
diff --git a/Triangulation_3/include/CGAL/Triangulation_hierarchy_3.h b/Triangulation_3/include/CGAL/Triangulation_hierarchy_3.h
index c3e41e74a31..f04da340346 100644
--- a/Triangulation_3/include/CGAL/Triangulation_hierarchy_3.h
+++ b/Triangulation_3/include/CGAL/Triangulation_hierarchy_3.h
@@ -22,6 +22,7 @@
 
 #include <CGAL/basic.h>
 #include <CGAL/Random.h>
+#include <CGAL/triangulation_assertions.h>
 #include <CGAL/Triangulation_hierarchy_vertex_base_3.h>
 
 CGAL_BEGIN_NAMESPACE