diff --git a/src/SparseTransform/Convert/ColoredDotWriter.cs b/src/SparseTransform/Convert/ColoredDotWriter.cs
index 6c9ca42eb043ca6d59fcd5d9e3b9d2d7a37a2f4c..afb7dea2d7418379014fa8f81c5a95e80e16e28e 100644
--- a/src/SparseTransform/Convert/ColoredDotWriter.cs
+++ b/src/SparseTransform/Convert/ColoredDotWriter.cs
@@ -38,17 +38,17 @@ namespace SparseTransform.Convert
         /// Labels the node with the respective colors determined by it's index. Overrides the method in DotWriter 
         /// </summary>
         /// <param name="node">the node to be labeld</param>
-        /// <param name="präfix">the paefix of the node-name (either 'c_' or 'r_'</param>
+        /// <param name="prefix">the paefix of the node-name (either 'c_' or 'r_'</param>
         /// <returns></returns>
-        public override String NodeLabel(GraphNode node, String präfix)
+        public override String NodeLabel(GraphNode node, String prefix)
         {
             if (textcolor || node.Color > 64)
             {
-                return "\t" + präfix + node.Index + "  [shape=circle, style=filled, label=\"" + präfix + node.Index + "\\n Farbe " + node.Color + "\"]";
+                return "\t" + prefix + node.Index + "  [shape=circle, style=filled, label=\"" + prefix + node.Index + "\\n Farbe " + node.Color + "\"]";
             }
             else
             {
-                return "\t" + präfix + node.Index + "  [shape=circle, style=filled, fillcolor=\"" + dictColor[node.Color] + "\"]";
+                return "\t" + prefix + node.Index + "  [shape=circle, style=filled, fillcolor=\"" + dictColor[node.Color] + "\"]";
             }
         }
     }
diff --git a/src/SparseTransform/Convert/DotWriter.cs b/src/SparseTransform/Convert/DotWriter.cs
index 66943527b371e9d32062c92eb6259c1f1bb53c57..58ac50c4c72b9e873aa58e120250005b1763a351 100644
--- a/src/SparseTransform/Convert/DotWriter.cs
+++ b/src/SparseTransform/Convert/DotWriter.cs
@@ -112,11 +112,11 @@ namespace SparseTransform.Convert
         /// auxiliary method for creating the dot-node label of graph node
         /// </summary>
         /// <param name="node"></param>
-        /// <param name="präfix">name of the node in the corresponding label</param>
+        /// <param name="prefix">name of the node in the corresponding label</param>
         /// <returns></returns>
-        public virtual String NodeLabel(GraphNode node, String präfix)
+        public virtual String NodeLabel(GraphNode node, String prefix)
         {
-            return "\t" + präfix + node.Index + "  [shape=circle, style=filled]";
+            return "\t" + prefix + node.Index + "  [shape=circle, style=filled]";
         }