diff --git a/README.txt b/README.txt
index 70f8a32..1e9ae45 100755
--- a/README.txt
+++ b/README.txt
@@ -50,6 +50,7 @@ But the simplest way is the next:
 3. Create Search Index, configure it. Add some fields into index and select few of them as facets. Select one of four ajax widgets for your facets. Enable option "Update results by ajax" for your facet.
 4. Create view based on your search index. Fastest way is select type of display "Page". Enable Ajax for your views display.
 5. Put block of your facet on the page where will be placed your view with search results.
+6. Module has integration with HTML5 browser history API. If you want to get this feature work for HTML4 browsers you should install libraries module (https://www.drupal.org/project/libraries) and download history.js (https://github.com/browserstate/history.js) library.
 Important - view should be processed earlier than facet block will be rendered. Otherwise facets will not work.
 
 5. CREDITS