diff --git a/irc.go b/irc.go
index 5e8455d..4e13886 100644
--- a/irc.go
+++ b/irc.go
@@ -13,6 +13,7 @@ https://tools.ietf.org/html/rfc2810
 https://tools.ietf.org/html/rfc2811
 https://tools.ietf.org/html/rfc2812
 https://tools.ietf.org/html/rfc2813
+The details of the client-to-client protocol (CTCP) can be found here: http://www.irchelp.org/irchelp/rfc/ctcpspec.html
 */
 
 package irc