diff --git a/modules/intersect.lua b/modules/intersect.lua
index 1fbab22..a81f12c 100644
--- a/modules/intersect.lua
+++ b/modules/intersect.lua
@@ -213,7 +213,7 @@ end
 
 -- Algorithm is ported from the C algorithm of
 -- Paul Bourke at http://local.wasp.uwa.edu.au/~pbourke/geometry/lineline3d/
--- Archive.org am hero \o/
+-- Archive.org am hero \o/ (https://web.archive.org/web/20120414063459/http://local.wasp.uwa.edu.au/~pbourke//geometry/lineline3d/)
 -- a[1] is a vec3
 -- a[2] is a vec3
 -- b[1] is a vec3