diff --git a/Bookshelf/Apostol.tex b/Bookshelf/Apostol.tex
index 45fbc10..40b7d49 100644
--- a/Bookshelf/Apostol.tex
+++ b/Bookshelf/Apostol.tex
@@ -65,7 +65,7 @@ Such a number $B$ is also known as the \textbf{greatest lower bound}.
 
 \end{definition}
 
-\section{\pending{Integrable}}%
+\section{\defined{Integrable}}%
 \hyperlabel{ref:integrable}
 
 Let $f$ be a function defined and bounded on $[a, b]$.
@@ -74,7 +74,7 @@ $f$ is said to be \textbf{integrable} if there exists one and only one number
 If $f$ is integrable on $[a, b]$, we say that the integral
   $\int_a^b f(x) \mathop{dx}$ \textbf{exists}.
 
-\section{\pending{Integral of a Bounded Function}}%
+\section{\defined{Integral of a Bounded Function}}%
 \hyperlabel{ref:integral-bounded-function}
 
 Let $f$ be a function defined and bounded on $[a, b]$.
@@ -102,7 +102,7 @@ The function $f$ is called the \textbf{integrand}, the numbers $a$ and $b$ are
   called the \textbf{limits of integration}, and the interval $[a, b]$ the
   \textbf{interval of integration}.
 
-\section{\pending{Integral of a Step Function}}%
+\section{\defined{Integral of a Step Function}}%
 \hyperlabel{ref:integral-step-function}
 
 Let $s$ be a \nameref{ref:step-function} defined on $[a, b]$, and let
@@ -118,7 +118,7 @@ The \textbf{integral of $s$ from $a$ to $b$}, denoted by the symbol
 If $a < b$, we define $\int_b^a s(x) \mathop{dx} = -\int_a^b s(x) \mathop{dx}$.
 We also define $\int_a^a s(x) \mathop{dx} = 0$.
 
-\section{\pending{Lower Integral}}%
+\section{\defined{Lower Integral}}%
 \hyperlabel{ref:lower-integral}
 
 Let $f$ be a function bounded on $[a, b]$ and $S$ denote the set of numbers
@@ -128,7 +128,7 @@ That is, let $$S = \left\{ \int_a^b s(x) \mathop{dx} : s \leq f \right\}.$$
 The number $\sup{S}$ is called the \textbf{lower integral of $f$}.
 It is denoted as $\ubar{I}(f)$.
 
-\section{\pending{Monotonic}}%
+\section{\defined{Monotonic}}%
 \hyperlabel{ref:monotonic}
 
 A function $f$ is called \textbf{monotonic} on set $S$ if it is increasing on
@@ -164,7 +164,7 @@ A collection of points satisfying \eqref{sec:partition-eq1} is called a
 
 \end{definition}
 
-\section{\pending{Refinement}}%
+\section{\defined{Refinement}}%
 \hyperlabel{ref:refinement}
 
 Let $P$ be a \nameref{ref:partition} of closed interval $[a, b]$.
@@ -213,7 +213,7 @@ Such a number $B$ is also known as the \textbf{least upper bound}.
 
 \end{definition}
 
-\section{\pending{Upper Integral}}%
+\section{\defined{Upper Integral}}%
 \hyperlabel{ref:upper-integral}
 
 Let $f$ be a function bounded on $[a, b]$ and $T$ denote the set of numbers