diff --git a/book/history/sourdough-history.tex b/book/history/sourdough-history.tex
index 373315b..f23b928 100644
--- a/book/history/sourdough-history.tex
+++ b/book/history/sourdough-history.tex
@@ -26,7 +26,7 @@ waters, another single-celled life form, \emph{archaea}, also thrived. These
 organisms inhabit extreme environments, from boiling vents to icy waters.
 
 \begin{figure}[!htb]
-\centering
+  \centering
   \input{figures/fig-life-planet-sourdough-timeline.tex}
   \caption[Sourdough microbiology timeline]{Timeline of significant events
     starting from the first day of Earth's existence,
@@ -57,12 +57,12 @@ Another 25~million years later, or our timeline's 2~days after the dinosaur
 extinction, humans appeared.
 
 A few hours later after the arrival of humans, a more subtle culinary
-revolution was unfolding. By \num{12000}~BC, just 5 seconds before our metaphorical
-midnight, the first sourdough breads were being baked in ancient Jordan. A blink of
-an eye later, or 4~seconds in our time compression, Pasteur's groundbreaking work
-with yeasts set the stage for modern bread-making. From the moment this book
-began to take shape to your current reading, only milliseconds have ticked
-by~\cite{Yong+2017}.
+revolution was unfolding. By \num{12000}~BC, just 5~seconds before our
+metaphorical midnight, the first sourdough breads were being baked in ancient
+Jordan. A blink of an eye later, or 4~seconds in our time compression,
+Pasteur's groundbreaking work with yeasts set the stage for modern
+bread-making. From the moment this book began to take shape to your current
+reading, only milliseconds have ticked by~\cite{Yong+2017}.
 
 Now delving deeper into the realm of sourdough, it can likely be traced to aforementioned
 Ancient Jordan~\cite{jordan+bread}. Looking at the earth's timeline sourdough
@@ -234,8 +234,8 @@ reason, none of the supermarket flour you buy today is single origin.  It is
 always blended to achieve exactly the same product throughout the years.
 
 Modern wheat, specifically the high-yielding and disease-resistant varieties
-commonly grown today, began to be developed in the mid-20th century. This
-period is often referred to as the \emph{Green Revolution.}
+commonly grown today, began to be developed in the mid-20\textsuperscript{th}
+century. This period is often referred to as the \emph{Green Revolution.}
 
 One of the key figures in this development was American scientist Norman
 Borlaug, who is credited with breeding high-yield wheat varieties,