diff -r 3b9496db3fb9 -r 3390e863d796 handouts/scala-ho.tex
--- a/handouts/scala-ho.tex	Tue Sep 26 14:07:29 2017 +0100
+++ b/handouts/scala-ho.tex	Tue Sep 26 14:08:49 2017 +0100
@@ -982,6 +982,12 @@
 inherited from the JVM that can be really annoying. For
 example a fixed stack size. One can work around this
 particular limitation, but why does one have to?
+More such `puzzles' can be found at
+
+\begin{center}
+  \url{http://scalapuzzlers.com} and
+  \url{http://latkin.org/blog/2017/05/02/when-the-scala-compiler-doesnt-help/}
+\end{center}
 
 Even if Scala has been a success in several high-profile
 companies, there is also a company (Yammer) that first used