diff --git a/harbour/tests/working/debugtst.prg b/harbour/tests/working/debugtst.prg
index 4f2248456c..047b080b6e 100644
--- a/harbour/tests/working/debugtst.prg
+++ b/harbour/tests/working/debugtst.prg
@@ -269,6 +269,9 @@ return aIn
 //
 // Warning : Recursion ahead !
 //
+// For instructions :
+// http://monty.cnri.reston.va.us/grail/demo/quicksort/quicksort.htm
+//
 function QuickSort( nLeft, nRight, aSort )
 
    local nI := nLeft