diff --git a/07_1_facetten_und_text_filter.md b/07_1_facetten_und_text_filter.md
index 614e391..0106caa 100644
--- a/07_1_facetten_und_text_filter.md
+++ b/07_1_facetten_und_text_filter.md
@@ -1,2 +1,3 @@
 # 7.1 Facetten und Text Filter
 
+Literatur: https://github.com/OpenRefine/OpenRefine/wiki/Faceting
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