diff --git a/C*DAV-explanations.md b/C*DAV-explanations.md
index 862e8d3..a44fa78 100644
--- a/C*DAV-explanations.md
+++ b/C*DAV-explanations.md
@@ -1,4 +1,5 @@
 (i) work in progress, for more see related RFCs
+* [https://www.rfc-editor.org/rfc/rfc4791](https://www.rfc-editor.org/rfc/rfc4791)
 
 # Calls by clients