diff --git a/01_4_open_discovery_initiative.md b/01_4_open_discovery_initiative.md
index 3a09ce7..0f4c2e8 100644
--- a/01_4_open_discovery_initiative.md
+++ b/01_4_open_discovery_initiative.md
@@ -6,6 +6,7 @@
 * NISO RP-19-2014: A Recommended Practice of the  National Information Standards Organization
 
 ## Auszug aus dem Papier (S. 20)
+http://www.niso.org/workrooms/odi/publications/rp/rp-19-2014
 
 [](http://www.niso.org/workrooms/odi/publications/rp/rp-19-2014)![](images/screenshot-niso-odi.png)