--- a/handouts/ho01.tex	Wed May 31 09:14:39 2017 +0100
+++ b/handouts/ho01.tex	Mon Jun 19 10:44:28 2017 +0100
@@ -18,6 +18,8 @@
 
 %% email validator
 %% http://www.ex-parrot.com/%7Epdw/Mail-RFC822-Address.html
+% https://jackfoxy.github.io/FsRegEx/emailregex.html
+
 
 %% regex testers
 % https://regex101.com