diff --git a/chapter04.tex b/chapter04.tex
index bec5ceb..6c4bdb3 100644
--- a/chapter04.tex
+++ b/chapter04.tex
@@ -473,7 +473,7 @@ element that corresponds to $a$ or the previous element.
 
 \index{bitset}
 
-A \texttt{bitset} is an array
+A \key{bitset} is an array
 where each element is either 0 or 1.
 For example, the following code creates
 a bitset that contains 10 elements:
@@ -528,7 +528,7 @@ cout << (a^b) << "\n"; // 1001101110
 
 \index{deque}
 
-A \texttt{deque} is a dynamic array
+A \key{deque} is a dynamic array
 whose size can be changed at both ends of the array.
 Like a vector, a deque provides the functions
 \texttt{push\_back} and \texttt{pop\_back}, but
@@ -556,7 +556,7 @@ elements is $O(1)$ on average at both ends.
 
 \index{stack}
 
-A \texttt{stack}
+A \key{stack}
 is a data structure that provides two
 $O(1)$ time operations:
 adding an element to the top,
@@ -578,7 +578,7 @@ cout << s.top(); // 2
 
 \index{queue}
 
-A \texttt{queue} also
+A \key{queue} also
 provides two $O(1)$ time operations:
 adding an element to the end of the queue,
 and removing the first element in the queue.
@@ -601,7 +601,7 @@ cout << s.front(); // 2
 \index{priority queue}
 \index{heap}
 
-A \texttt{priority\_queue}
+A \key{priority queue}
 maintains a set of elements.
 The supported operations are insertion and,
 depending on the type of the queue,