Merge pull request #67 from EFanZh/patch-1

Added upquote package

book.tex

@@ -14,6 +14,7 @@
 \usepackage{tcolorbox}
 \usepackage{color}
 %\usepackage{ifthen}
+\usepackage{upquote}
 
 
 \definecolor{lightgray}{gray}{1}