add citations to cgal_manual.bib

Documentation/doc/biblio/cgal_manual.bib

@@ -299,6 +299,17 @@ Boissonnat}
   ,update       = "98.01 schirra"
 }
 
+@inproceedings{cgal:cad-vsa-04,
+  title={Variational shape approximation},
+  author={Cohen-Steiner, David and Alliez, Pierre and Desbrun, Mathieu},
+  booktitle={ACM Transactions on Graphics (TOG)},
+  volume={23},
+  number={3},
+  pages={905--914},
+  year={2004},
+  organization={ACM}
+}
+
 @inproceedings{cgal::c-mssbo-04,
   author={Chen, L.},
   title={{Mesh Smoothing Schemes based on Optimal Delaunay Triangulations}},
@@ -1320,6 +1331,17 @@ Voronoi diagram"
   ,update       = "97.04 kettner"
 }
 
+@article{cgal:l-lsqp-82,
+  title={Least squares quantization in PCM},
+  author={Lloyd, Stuart},
+  journal={IEEE transactions on information theory},
+  volume={28},
+  number={2},
+  pages={129--137},
+  year={1982},
+  publisher={IEEE}
+}
+
 @InProceedings{ cgal:lprm-lscm-02,
    author    = {Bruno L{\'e}vy and Sylvain Petitjean and Nicolas Ray
                 and J{\'e}rome Maillot},