added references for Polynomial manual

Manual/doc_tex/Manual/geom.bib

@@ -49446,6 +49446,15 @@ library."
 , update =	"93.09 tamassia"
 }
 
+@Article{d-osa-00,
+  author =       {Lionel Ducos},
+  title =        {Optimizations of the Subresultant Algorithm},
+  journal =      {Journal of Pure and Applied Algebra},
+  year =         2000,
+  volume =       145,
+  pages =        {149--163}
+}
+
 @book{dh-pcsa-73
 , author =	"R. O. Duda and P. E. Hart"
 , title =	"Pattern Classification and Scene Analysis"
@@ -87793,6 +87802,14 @@ the R*-tree."
 , update =	"99.11 bibrelex"
 }
 
+@Article{k-dfcosubm-09,
+  author =       {Michael Kerber},
+  title =        {Division-Free Computation of Subresultants Using Bezout Matrices},
+  journal =      {International Journal of Computer Mathematics},
+  year =         2009,
+  note =         {in print; a technical report with the same name appeared as MPI-I-2006-1-006, Saabr\"ucken, Germany}
+}
+
 @book{k-hdsl-1877
 , author =	"Alfred Bray Kempe"
 , title =	"How to Draw a Straight Line; a Lecture on Linkages"
@@ -151743,3 +151760,4 @@ amplification and suppression of local contrast. Contains C code."
 , publisher =   "Cambridge University Press"
 , year =        1999
 }
+

Polynomial/doc_tex/Polynomial_ref/polynomial_utils.tex

@@ -817,11 +817,11 @@ The computation method depends on the algebraic category of
 \ccc{PolynomialTraits_d::Coefficient_type}.
 if it models \ccc{CGAL::IntegralDomain}, 
 the subresultants are computed
-by a pseudo-division approach~\cite{ducos-optimizations}. 
+by a pseudo-division approach~\cite{d-osa-00}. 
 If they only model a
 \ccc{CGAL::IntegralDomainWithoutDivision}, the subresultants
 are computed by evaluating the determinants directly, avoiding divisions
-completely~\cite{kerber-division}.
+completely~\cite{k-dfcosubm-09}.
 
 \ccOperations
 \ccFunction{template<typename Polynomial_traits_d,typename OutputIterator>