From f67a088cce1621f0171179d298930a4dcc7af875 Mon Sep 17 00:00:00 2001
From: Matt Terry <matt.terry@gmail.com>
Date: Tue, 23 Jul 2013 09:33:55 -0700
Subject: [PATCH]  references

---
 skimage/color/delta_e.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/skimage/color/delta_e.py b/skimage/color/delta_e.py
index 9f8cd2e8..70bbb99b 100644
--- a/skimage/color/delta_e.py
+++ b/skimage/color/delta_e.py
@@ -18,6 +18,7 @@ The delta-E notation comes from the German word for "Sensation" (Empfindung).
 
 Reference
 ---------
+http://en.wikipedia.org/wiki/Color_difference
 
 """
 from __future__ import division