diff --git a/src/Chapter13.Tests/Listing13.21.StaticAnonymousFunctions.Tests.cs b/src/Chapter13.Tests/Listing13.21.StaticAnonymousFunctions.Tests.cs
new file mode 100644
index 000000000..9a7a49cfa
--- /dev/null
+++ b/src/Chapter13.Tests/Listing13.21.StaticAnonymousFunctions.Tests.cs
@@ -0,0 +1,17 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using AddisonWesley.Michaelis.EssentialCSharp.Shared.Tests;
+
+namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_21.Tests;
+
+[TestClass]
+public class ProgramTests
+{
+    [TestMethod]
+    public async Task StaticAnonymousFunctionBehavior()
+    {
+        await CompilerAssert.CompileAsync(
+            new string[] { "Listing13.21.StaticAnonymousFunctions.cs",
+                "Listing13.11.UsingADifferentFuncCompatibleMethod.cs"},
+            new string[] { "CS8820" } );
+    }
+}
diff --git a/src/Chapter13.Tests/Listing13.21.Tests.cs b/src/Chapter13.Tests/Listing13.22.CSharpEquivalentOfCILCodeGeneratedByCompilerForOuterVariables.Tests.cs
similarity index 82%
rename from src/Chapter13.Tests/Listing13.21.Tests.cs
rename to src/Chapter13.Tests/Listing13.22.CSharpEquivalentOfCILCodeGeneratedByCompilerForOuterVariables.Tests.cs
index 546b90cea..b2e7e8e7b 100644
--- a/src/Chapter13.Tests/Listing13.21.Tests.cs
+++ b/src/Chapter13.Tests/Listing13.22.CSharpEquivalentOfCILCodeGeneratedByCompilerForOuterVariables.Tests.cs
@@ -1,6 +1,6 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 
-namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_21.Tests;
+namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_22.Tests;
 
 [TestClass]
 public class ProgramTests
@@ -13,4 +13,4 @@ public void MainTest()
         IntelliTect.TestTools.Console.ConsoleAssert.Expect(
             expected, Program.Main);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Chapter13.Tests/Listing13.22.Tests.cs b/src/Chapter13.Tests/Listing13.23.CapturingLoopVariablesCSharpFive.Tests.cs
similarity index 82%
rename from src/Chapter13.Tests/Listing13.22.Tests.cs
rename to src/Chapter13.Tests/Listing13.23.CapturingLoopVariablesCSharpFive.Tests.cs
index a4b843c07..ea071d8ed 100644
--- a/src/Chapter13.Tests/Listing13.22.Tests.cs
+++ b/src/Chapter13.Tests/Listing13.23.CapturingLoopVariablesCSharpFive.Tests.cs
@@ -1,6 +1,6 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 
-namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_22.Tests;
+namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_23.Tests;
 
 [TestClass]
 public class ProgramTests
@@ -13,4 +13,4 @@ public void MainTest()
         IntelliTect.TestTools.Console.ConsoleAssert.Expect(
             expected, CaptureLoop.Main);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Chapter13.Tests/Listing13.23.Tests.cs b/src/Chapter13.Tests/Listing13.24.LoopVariableWorkaroundBeforeCSharpFive.Tests.cs
similarity index 83%
rename from src/Chapter13.Tests/Listing13.23.Tests.cs
rename to src/Chapter13.Tests/Listing13.24.LoopVariableWorkaroundBeforeCSharpFive.Tests.cs
index fe0054125..af347c445 100644
--- a/src/Chapter13.Tests/Listing13.23.Tests.cs
+++ b/src/Chapter13.Tests/Listing13.24.LoopVariableWorkaroundBeforeCSharpFive.Tests.cs
@@ -1,6 +1,6 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 
-namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_23.Tests;
+namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_24.Tests;
 
 [TestClass]
 public class ProgramTests
@@ -13,4 +13,4 @@ public void MainTest()
         IntelliTect.TestTools.Console.ConsoleAssert.Expect(
             expected, DoNotCaptureLoop.Main);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Chapter13.Tests/Listing13.25.ExamingingAnExpressionTree.Tests.cs b/src/Chapter13.Tests/Listing13.26.ExamingingAnExpressionTree.Tests.cs
similarity index 89%
rename from src/Chapter13.Tests/Listing13.25.ExamingingAnExpressionTree.Tests.cs
rename to src/Chapter13.Tests/Listing13.26.ExamingingAnExpressionTree.Tests.cs
index ad22f01cb..44d948d32 100644
--- a/src/Chapter13.Tests/Listing13.25.ExamingingAnExpressionTree.Tests.cs
+++ b/src/Chapter13.Tests/Listing13.26.ExamingingAnExpressionTree.Tests.cs
@@ -1,6 +1,6 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 
-namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_25.Tests;
+namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_26.Tests;
 
 [TestClass]
 public class ProgramTests
@@ -30,4 +30,4 @@ public void Main_ExamingingAnExpressTree()
             Program.Main();
         });
     }
-}
\ No newline at end of file
+}
diff --git a/src/Chapter13/Listing13.21.StaticAnonymousFunctions.cs b/src/Chapter13/Listing13.21.StaticAnonymousFunctions.cs
new file mode 100644
index 000000000..122d08346
--- /dev/null
+++ b/src/Chapter13/Listing13.21.StaticAnonymousFunctions.cs
@@ -0,0 +1,50 @@
+namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_21;
+
+using System;
+using Listing13_11;
+public class Program
+{
+    public static void Main()
+    {
+        int[] items = new int[5];
+
+        for (int i = 0; i < items.Length; i++)
+        {
+            Console.Write("Enter an integer:");
+            string? text = Console.ReadLine();
+            if (!int.TryParse(text, out items[i]))
+            {
+                Console.WriteLine($"'{text}' is not a valid integer.");
+                return;
+            }
+        }
+
+        #region INCLUDE
+        int comparisonCount = 0;
+        
+        DelegateSample.BubbleSort(items,
+        #region HIGHLIGHT
+            static (int first, int second) =>
+        #endregion HIGHLIGHT
+            {
+                #if COMPILEERROR // EXCLUDE
+                // Error CS8820: A static anonymous function
+                // cannot contain a reference to comparisonCount.
+                comparisonCount++;
+                #endif // COMPILEERROR EXCLUDE
+                return first < second;
+            }
+        );
+
+        for (int i = 0; i < items.Length; i++)
+        {
+            Console.WriteLine(items[i]);
+        }
+
+        #region HIGHLIGHT
+        Console.WriteLine("Items were compared {0} times.",
+            comparisonCount);
+        #endregion HIGHLIGHT
+    }
+}
+#endregion INCLUDE
diff --git a/src/Chapter13/Listing13.21.CSharpEquivalentOfCILCodeGeneratedByCompilerForOuterVariables.cs b/src/Chapter13/Listing13.22.CSharpEquivalentOfCILCodeGeneratedByCompilerForOuterVariables.cs
similarity index 94%
rename from src/Chapter13/Listing13.21.CSharpEquivalentOfCILCodeGeneratedByCompilerForOuterVariables.cs
rename to src/Chapter13/Listing13.22.CSharpEquivalentOfCILCodeGeneratedByCompilerForOuterVariables.cs
index bd41ee24c..260cb8dbc 100644
--- a/src/Chapter13/Listing13.21.CSharpEquivalentOfCILCodeGeneratedByCompilerForOuterVariables.cs
+++ b/src/Chapter13/Listing13.22.CSharpEquivalentOfCILCodeGeneratedByCompilerForOuterVariables.cs
@@ -1,4 +1,4 @@
-namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_21;
+namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_22;
 
 using System;
 using Listing13_11;
diff --git a/src/Chapter13/Listing13.22.CapturingLoopVariablesCSharpFive.cs b/src/Chapter13/Listing13.23.CapturingLoopVariablesCSharpFive.cs
similarity index 85%
rename from src/Chapter13/Listing13.22.CapturingLoopVariablesCSharpFive.cs
rename to src/Chapter13/Listing13.23.CapturingLoopVariablesCSharpFive.cs
index e92297fc7..c31c6a2b2 100644
--- a/src/Chapter13/Listing13.22.CapturingLoopVariablesCSharpFive.cs
+++ b/src/Chapter13/Listing13.23.CapturingLoopVariablesCSharpFive.cs
@@ -1,4 +1,4 @@
-namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_22;
+namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_23;
 
 using System;
 using System.Collections.Generic;
diff --git a/src/Chapter13/Listing13.23.LoopVariableWorkaroundBeforeCSharpFive.cs b/src/Chapter13/Listing13.24.LoopVariableWorkaroundBeforeCSharpFive.cs
similarity index 88%
rename from src/Chapter13/Listing13.23.LoopVariableWorkaroundBeforeCSharpFive.cs
rename to src/Chapter13/Listing13.24.LoopVariableWorkaroundBeforeCSharpFive.cs
index d26f027eb..da100430f 100644
--- a/src/Chapter13/Listing13.23.LoopVariableWorkaroundBeforeCSharpFive.cs
+++ b/src/Chapter13/Listing13.24.LoopVariableWorkaroundBeforeCSharpFive.cs
@@ -1,4 +1,4 @@
-namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_23;
+namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_24;
 
 using System;
 using System.Collections.Generic;
diff --git a/src/Chapter13/Listing13.24.ConvertingExpressionTreeToSqlWhereClause.cs b/src/Chapter13/Listing13.25.ConvertingExpressionTreeToSqlWhereClause.cs
similarity index 72%
rename from src/Chapter13/Listing13.24.ConvertingExpressionTreeToSqlWhereClause.cs
rename to src/Chapter13/Listing13.25.ConvertingExpressionTreeToSqlWhereClause.cs
index fe5a4d399..9a3b47b62 100644
--- a/src/Chapter13/Listing13.24.ConvertingExpressionTreeToSqlWhereClause.cs
+++ b/src/Chapter13/Listing13.25.ConvertingExpressionTreeToSqlWhereClause.cs
@@ -1,4 +1,4 @@
-namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_24;
+namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_25;
 
 /*
 #region INCLUDE
@@ -8,4 +8,4 @@
 SQL WHERE CLAUSE:
     select * from Person where upper(Name) = 'INIGO MONTOYA';
 #endregion INCLUDE
- */
\ No newline at end of file
+ */
diff --git a/src/Chapter13/Listing13.25.ExamingingAnExpressionTree.cs b/src/Chapter13/Listing13.26.ExamingingAnExpressionTree.cs
similarity index 95%
rename from src/Chapter13/Listing13.25.ExamingingAnExpressionTree.cs
rename to src/Chapter13/Listing13.26.ExamingingAnExpressionTree.cs
index 0536d1a27..9b1500249 100644
--- a/src/Chapter13/Listing13.25.ExamingingAnExpressionTree.cs
+++ b/src/Chapter13/Listing13.26.ExamingingAnExpressionTree.cs
@@ -1,4 +1,4 @@
-namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_25;
+namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter13.Listing13_26;
 
 #region INCLUDE
 using System;
@@ -58,4 +58,4 @@ private static string NodeToString(Expression expression) =>
                 " (" + expression.NodeType.ToString() + ")",
         };
     #endregion INCLUDE
-}
\ No newline at end of file
+}