diff --git a/webapp/lsp/set.xqm b/webapp/lsp/set.xqm
index 4157dcb..c53a246 100644
--- a/webapp/lsp/set.xqm
+++ b/webapp/lsp/set.xqm
@@ -1,6 +1,7 @@
 module namespace set = "http://qt4cg.org/atomic-set";
    
    (:
+   https://qt4cg.org/specifications/xquery-40/xquery-40.html#id-atomic-set-example
       This package defines a type set:atomic-set which represents
       a set of distinct atomic items. Atomic items are considered
       distinct based on the comparison function fn:atomic-equal.