diff --git a/helm-dictionary.el b/helm-dictionary.el
index 3885a59..093d716 100644
--- a/helm-dictionary.el
+++ b/helm-dictionary.el
@@ -130,17 +130,20 @@
   :type  'file)
 
 (defcustom helm-dictionary-online-dicts
-    '(("translate.reference.com de->eng" .
-       "http://translate.reference.com/translate?query=%s&src=de&dst=en")
-      ("translate.reference.com eng->de" .
-       "http://translate.reference.com/translate?query=%s&src=en&dst=de")
-      ("leo eng<->de" .
-       "http://dict.leo.org/ende?lp=ende&lang=de&search=%s")
-      ("en.wiktionary.org" . "http://en.wiktionary.org/wiki/%s")
-      ("de.wiktionary.org" . "http://de.wiktionary.org/wiki/%s")
-      ("linguee-eng<->de"    . "http://www.linguee.de/deutsch-englisch/search\
+  '(("translate.reference.com de->eng" .
+     "http://translate.reference.com/translate?query=%s&src=de&dst=en")
+    ("translate.reference.com eng->de" .
+     "http://translate.reference.com/translate?query=%s&src=en&dst=de")
+    ("leo eng<->de" .
+     "http://dict.leo.org/ende?lp=ende&lang=de&search=%s")
+    ("en.wiktionary.org" . "http://en.wiktionary.org/wiki/%s")
+    ("de.wiktionary.org" . "http://de.wiktionary.org/wiki/%s")
+    ("linguee-eng<->de" . "http://www.linguee.de/deutsch-englisch/search\
 ?sourceoverride=none&source=auto&query=%s"))
-    "Alist of online dictionaries.")
+  "Alist of online dictionaries.  The key of each entry is the
+name of the online dictionary.  The value is the URL used for
+retrieving results.  This URL must contain a %s at the position
+where the search term should be inserted.")
 
 (defcustom helm-dictionary-browser-function nil
   "The browser that is used to access online dictionaries.  If