diff --git a/gauge-fields-knots-and-gravity.md b/gauge-fields-knots-and-gravity.md
index f23228e75..8d7ddef4a 100644
--- a/gauge-fields-knots-and-gravity.md
+++ b/gauge-fields-knots-and-gravity.md
@@ -2,4 +2,5 @@
 
 - a [[book]]
   - [[go]] https://www.worldscientific.com/worldscibooks/10.1142/2324
+  - [[chapter]] https://www.worldscientific.com/doi/suppl/10.1142/2324/suppl_file/2324_chap01.pdf