diff --git a/Constrained_triangulation_3/doc/Constrained_triangulation_3/Constrained_triangulation_3.txt b/Constrained_triangulation_3/doc/Constrained_triangulation_3/Constrained_triangulation_3.txt
index 7bae0a94a5c..fd346577378 100644
--- a/Constrained_triangulation_3/doc/Constrained_triangulation_3/Constrained_triangulation_3.txt
+++ b/Constrained_triangulation_3/doc/Constrained_triangulation_3/Constrained_triangulation_3.txt
@@ -46,7 +46,7 @@ that satisfy the following properties:
   shared vertex.
 - The boundary of each polygonal face in the PLC is an ordered list of vertices from the PLC, forming
   one closed loop.
-- Each polygonal face must be a simple polygon, i.e. its edges don't intersect,
+- Each polygonal face must be a simple polygon, i.e., its edges don't intersect,
   except consecutive edges, which intersect at their common vertex.
 - Each polygonal face may have one or more holes, each of them also represented by an ordered list of vertices
   from the PLC, forming a closed loop.
@@ -82,7 +82,7 @@ joining them does not intersect any polygonal face of the PLC, except for polygo
 the segment.
 
 In 3D, constrained triangulations do not always exist. This can be demonstrated using the example of
-Schönhardt polyhedra \cgalCite{schonhardt1928zerlegung} (see \cgalFigureRef{CT_3_schonhardt_fig}),
+Schönhardt polyhedra \cgalCite{s-udzvd-28} (see \cgalFigureRef{CT_3_schonhardt_fig}),
 \cgalCite{b-ip-48a}. Shewchuk \cgalCite{cgal:shewchuk1998condition} demonstrated that for any PLC,
 there exists a refined
 version of the original PLC that admits a constrained Delaunay triangulation. This refinement is
diff --git a/Documentation/doc/biblio/geom.bib b/Documentation/doc/biblio/geom.bib
index b719d34af08..b1e2985919c 100644
--- a/Documentation/doc/biblio/geom.bib
+++ b/Documentation/doc/biblio/geom.bib
@@ -152087,16 +152087,6 @@ keywords = {polygonal surface mesh, Surface reconstruction, kinetic framework, s
   publisher={Elsevier}
 }
 
-@article{schonhardt1928zerlegung,
-  title={{\"U}ber die Zerlegung von Dreieckspolyedern in Tetraeder},
-  author={Sch{\"o}nhardt, Erich},
-  journal={Mathematische Annalen},
-  volume={98},
-  number={1},
-  pages={309--312},
-  year={1928},
-  publisher={Springer}
-}
 
 @inproceedings{si2005meshing,
   title={Meshing piecewise linear complexes by constrained {Delaunay} tetrahedralizations},