diff --git a/ch21/more_fancy b/ch21/more_fancy
index ff69941..df9e0e5 100755
Binary files a/ch21/more_fancy and b/ch21/more_fancy differ
diff --git a/ch21/pointer_virtual b/ch21/pointer_virtual
index e30b16b..166657e 100755
Binary files a/ch21/pointer_virtual and b/ch21/pointer_virtual differ
diff --git a/ch23/reference_virtual b/ch23/reference_virtual
new file mode 100755
index 0000000..b832569
Binary files /dev/null and b/ch23/reference_virtual differ
diff --git a/ch23/reference_virtual.cc b/ch23/reference_virtual.cc
new file mode 100644
index 0000000..244efb3
--- /dev/null
+++ b/ch23/reference_virtual.cc
@@ -0,0 +1,57 @@
+#include <iostream>
+
+using namespace std;
+
+class FirstClass {     
+ public:
+  void print1() {
+    cout << "FirstClass::print1()" << endl;
+  }
+  virtual void print2() {
+    cout << "FirstClass::print2()" << endl;
+  }
+  void print3() {
+    print1();
+    print2();
+    cout << endl;
+  }
+};
+
+class SecondClass : public FirstClass {     
+ public:
+  void print1() {
+    cout << "SecondClass::print1()" << endl;
+  }
+  virtual void print2() {
+    cout << "SecondClass::print2()" << endl;
+  }
+};
+
+class ThirdClass : public SecondClass {     
+ public:
+  void print1() {
+    cout << "ThirdClass::print1()" << endl;
+  }
+  virtual void print2() {
+    cout << "ThirdClass::print2()" << endl;
+  }
+};
+
+int main(int argc, char **argv) {
+  FirstClass f1;
+  f1.print1();
+  f1.print2();
+  f1.print3();
+
+  SecondClass f2;
+  f2.print1();
+  f2.print2();
+  f2.print3();
+
+  ThirdClass f3;
+  f3.print1();
+  f3.print2();
+  f3.print3();
+  
+  return 0;
+}
diff --git a/ch25/design_pattern.cc b/ch25/design_pattern.cc
index 31d7110..91bfc03 100644
--- a/ch25/design_pattern.cc
+++ b/ch25/design_pattern.cc
@@ -99,7 +99,3 @@ class IntSetList : public IntSet {
   Node *first;
 };
 
-
-
-
-