diff --git a/slides/chapter-11.de.md b/slides/chapter-11.de.md
index 7a73856..4e068ab 100644
--- a/slides/chapter-11.de.md
+++ b/slides/chapter-11.de.md
@@ -84,6 +84,7 @@ Weitere Materialien
 @content
 * [Einführung](https://www.overleaf.com/learn/latex/Code_listing#Reference_guide) in das Paket
 * offizielle [Dokumentation](https://www.overleaf.com/learn/latex/Code_listing#Reference_guide)
+* vordefinierte [UTF-8-Konfiguration](https://en.wikibooks.org/wiki/LaTeX/Source_Code_Listings#Encoding_issue)
 * das Paket [`xcolor`](https://www.overleaf.com/learn/latex/Using_colours_in_LaTeX) für Farben
 * zwei [Themes](https://github.com/jez/latex-solarized) im solarized-Stil für `listings`
 
diff --git a/slides/chapter-11.en.md b/slides/chapter-11.en.md
index 5435448..358cd6c 100644
--- a/slides/chapter-11.en.md
+++ b/slides/chapter-11.en.md
@@ -84,6 +84,7 @@ Further resources
 @content
 * [introduction](https://www.overleaf.com/learn/latex/Code_listing#Reference_guide) to the package
 * official [documentation](https://www.overleaf.com/learn/latex/Code_listing#Reference_guide)
+* predefined [UTF-8 configuration](https://en.wikibooks.org/wiki/LaTeX/Source_Code_Listings#Encoding_issue)
 * [`xcolor` package](https://www.overleaf.com/learn/latex/Using_colours_in_LaTeX) for colors
 * two [solarized themes](https://github.com/jez/latex-solarized) for `listings`