Configure lstset/literate for German umlauts in lstlistings.

chapters/recommendations/recommendations.tex

@@ -61,6 +61,16 @@ ngermane,american,
 
 \setlength\parindent{0pt}
 
+\lstset{literate=%
+  {Ö}{{\"O}}1
+  {Ä}{{\"A}}1
+  {Ü}{{\"U}}1
+  {ß}{{\ss}}1
+  {ü}{{\"u}}1
+  {ä}{{\"a}}1
+  {ö}{{\"o}}1
+}
+
 %----------------------------------------------------------------------------------------
 
 \begin{document}