BibTeX, biblatex and biber ⇒ BibLaTeX Counter of References

[degun]

Hello,
first I apologize for my bad english. I am french.

I use biblatex

I want to create a pdf file containing a very big bibliography file with the nocite(*) command
and separate this bibliography in several parts based on the categories : books, articles, etc ... (for exemple)
and sort it.

I do this without any problem.

Code: Select all

\usepackage[natbib=true, bibstyle=authoryear,sorting=ydnt,defernums=true]{biblatex} 
\bibliography{mybib} 

\defbibheading{Article}{\section*{Peer reviewed articles}} 
\defbibheading{Books}{\section*{Books}} 

\begin{document}
\printbibliography[heading=Article,keyword=primary]
\printbibliography[heading=Books,keyword=secondary]
\nocite{*}
\end{document}

Now, I just want to print each number of references before each category

Exemple :

Articles
The database contains xxx articles referenced
......

Books
The database contains yyy books referenced
......

I found a lot of counters in the biblatex docimentation (listcount, citetotal, instcount, ...)
but when I try to display them by the commands
\value{counter} or \thecounter
I get an error on value 0

How can I display theses values or is it another method ?

Thanks.