diff --git a/docs/404.md b/docs/404.md
index 99f5f954..b682ad9c 100644
--- a/docs/404.md
+++ b/docs/404.md
@@ -4,18 +4,24 @@
 {% include fallback.html %}
 
 Over time, some pages moved to new locations or content merged into other pages.
-Below some old names of pages and links to their new locations
-or to pages with similar content.
+Below links to new locations or to pages with similar content.
 You can also drop a note at the [user group] for guidance to recover.
 
 [user group]: https://groups.io/g/groundforge
 
+Offline references
+
+* OIDFA 4-2019, page 29 [reference](https://github.com/d-bl/GroundForge/blob/oidfa-article/docs/help/index.md#BK-31) 
+* Die Spitze 1/2020, Seite 50 [Literaturhinweise](https://github.com/d-bl/GroundForge/blob/oidfa-article/docs/help/DE.md#BK-31)
+* [Powerpoint](https://github.com/d-bl/GroundForge/blob/e6464920/docs/help/NL.pdf)  mai 2017 at "_de Waaier_"
+
+Online references
+
+* [help](/GroundForge-help/) `GroundForge/help` -> `GroundForge-help`: the slash became a dash
 * gallery, thumbs, Tesselace Index -> [tesselace-to-gf](/tesseLace-to-gf)
 * Whiting index -> [gw-lace-to-gf](/gw-lace-to-gf)
-* [Powerpoint](https://github.com/d-bl/GroundForge/blob/e6464920/docs/help/NL.pdf), Dutch presented in 2017
 * [recursive](/GroundForge/tiles) (apply wand in _Thread diagram as pair diagram_ section) 
 * [rose](/GroundForge/sheet.html?patch=5831%20-4-7;bricks&patch=-437%2034-7;bricks&patch=4830%20--77;bricks)
 * [stitches](/GroundForge-help/Replace)
-* [help](/GroundForge-help/) `GroundForge/help` -> `GroundForge-help`: the slash became a dash
 
 ![](images/tipped-over.png)
\ No newline at end of file