diff --git a/kkkk.pdf b/kkkk.pdf
index dfe06ea..bce637c 100644
Binary files a/kkkk.pdf and b/kkkk.pdf differ
diff --git a/kkkk.tex b/kkkk.tex
index c40b0c3..4615407 100644
--- a/kkkk.tex
+++ b/kkkk.tex
@@ -1,6 +1,6 @@
 \documentclass[twoside,12pt,a4paper,english]{book}
 
-% \includeonly{luku21}
+%\includeonly{luku22}
 
 \usepackage[english]{babel}
 \usepackage[utf8]{inputenc}
@@ -96,7 +96,7 @@
 \include{luku20}
 \part{Advanced topics}
 \include{luku21}
-% \include{luku22}
+\include{luku22}
 % \include{luku23}
 % \include{luku24}
 % \include{luku25}
diff --git a/luku22.tex b/luku22.tex
index 1fd247f..96f6ccb 100644
--- a/luku22.tex
+++ b/luku22.tex
@@ -65,7 +65,7 @@ which is based on the fact that there are $n-1$
 possible positions for +-signs in the sum,
 and we can choose any subset of them.
 
-\section{Binomial coefficient}
+\section{Binomial coefficients}
 
 \index{binomial coefficient}