diff --git a/ch09/README.md b/ch09/README.md
index 39a667d6..e5cb5d3d 100644
--- a/ch09/README.md
+++ b/ch09/README.md
@@ -235,7 +235,7 @@ void insert(forward_list<string> &flst, string find, string insrt)
 vec.resize(100) do? What if we next wrote vec.resize(10)?
 
 ```cpp
-vec.resize(100);    // adds 75 elements of value 0 to the back of vec
+vec.resize(100);    // adds 75 items to the back of vec. These added items are value initialized.
 vec.resize(10);     // erases 90 elements from the back of vec
 ```
 
diff --git a/ch09/ex9_33.cpp b/ch09/ex9_33.cpp
index 60735153..5f474663 100644
--- a/ch09/ex9_33.cpp
+++ b/ch09/ex9_33.cpp
@@ -8,7 +8,8 @@
 //  @Brief  In the final example in this section what would happen 
 //          if we did not assign the result of insert to begin? 
 //          Write a program that omits this assignment to see if your expectation was correct.  
-//  @Answer crash, cause the iterator is invalid after insert.
+//  @Answer crash, cause the iterator is invalid after insert. Because Iterators, pointers, and references to a
+//          vector or string are invalid if the container was reallocated. 
 
 #include <iostream>
 #include <vector>
diff --git a/ch09/ex9_52.cpp b/ch09/ex9_52.cpp
index bfab9c30..831ea1d8 100644
--- a/ch09/ex9_52.cpp
+++ b/ch09/ex9_52.cpp
@@ -1,15 +1,15 @@
 //
 //  ex9_52.cpp
-//  Exercise 9.52 
+//  Exercise 9.52
 //
 //  Created by pezy on 12/5/14.
 //  Copyright (c) 2014 pezy. All rights reserved.
 //
-//  @Brief  Use a stack to process parenthesized expressions. 
-//          When you see an open parenthesis, note that it was seen. 
-//          When you see a close parenthesis after an open parenthesis, 
-//          pop elements down to and including the open parenthesis off the stack. 
-//          push a value onto the stack to indicate that a parenthesized expression was replaced. 
+//  @Brief  Use a stack to process parenthesized expressions.
+//          When you see an open parenthesis, note that it was seen.
+//          When you see a close parenthesis after an open parenthesis,
+//          pop elements down to and including the open parenthesis off the stack.
+//          push a value onto the stack to indicate that a parenthesized expression was replaced.
 
 #include <stack>
 using std::stack;
@@ -22,12 +22,13 @@ using std::cout; using std::endl;
 
 int main()
 {
-    string expr = "This is (Mooophy(awesome)((((wooooooooo))))) and (ocxs) over";
-    char repl = '#';
+    auto & expr = "This is (Mooophy(awesome)((((wooooooooo))))) and (ocxs) over";
+    auto   repl = '#';
+    auto   seen = 0;
+
     stack<char> stk;
-    int seen = 0;
 
-    for ( auto c : expr ) {
+    for (auto c : expr) {
         stk.push(c);
         if ( c == '(' ) ++seen; // open
         if ( seen && c == ')' ) { // pop elements down to the stack
diff --git a/ch10/ex10_07.cpp b/ch10/ex10_07.cpp
index 939ceb59..57403d3d 100644
--- a/ch10/ex10_07.cpp
+++ b/ch10/ex10_07.cpp
@@ -36,6 +36,9 @@ int main()
     // the destination is large enough to hold the number of elements being written.
     copy(lst.cbegin(), lst.cend(), vec.begin());
     
+    //another way to fix bug
+    //copy(lst.cbegin(), lst.cend(), back_inserter(vec));
+    
     // (b)
     vector<int> v;
     v.reserve(10);