diff --git a/ulo/coq-cut.sh b/ulo/coq-cut.sh
index 7490d98be573a99d0f1903ec43cd8b690cb79efc..1f6ee805e7ed3cafeacd427a4a07a5ff38c2b5b7 100755
--- a/ulo/coq-cut.sh
+++ b/ulo/coq-cut.sh
@@ -1,9 +1,11 @@
 #! /bin/sh
 
-# cut out some components from the rdf files exported from Coq
+# cut out some components from the rdf files exported from Coq [1]
 # that GraphDB does not like; right now I don't know if they
 # are important or if they can be skipped, but I just want a working
 # prototype first of all
+#
+# [1] https://gl.mathhub.info/Coqxml
 
 set -eu