diff --git a/content/docs/020-permissions/index.md b/content/docs/020-permissions/index.md
index aceeab9..c17ae5f 100644
--- a/content/docs/020-permissions/index.md
+++ b/content/docs/020-permissions/index.md
@@ -56,7 +56,7 @@ There may also be restrictions concerning certain species of birds in the nestin
 If you have access to *The Ringing World*, Alistair Whybrow has two articles describing the installation of swift boxes at Kingsteignton, Devon: *Bell chambers offer sanctuary for swifts*, 7 December 2018 (p1224) and *Swift boxes have success in second year!*, 29 November 2019 (p1172).
 {{< /hint >}}
 
-Alistair has also produced a more detailed article on *Swift Boxes on Church Bell Towers* which is available as a PDF download [here](static/swifts-v1.pdf).
+Alistair has also produced a more detailed article on *Swift Boxes on Church Bell Towers* which is available as a PDF download [here](static/swifts-v1-4.pdf).
 
 ## Other Jurisdictions