diff --git a/content/3.defense-systems/cas.md b/content/3.defense-systems/cas.md
index 2b5f2363961d9e5be93d1f0f1711121018963ef2..665e5b5cab13b0b4aa3fcbb98d2b473e9dfe9e2b 100644
--- a/content/3.defense-systems/cas.md
+++ b/content/3.defense-systems/cas.md
@@ -10,6 +10,8 @@ tableColumns:
 
 # CRISPR-Cas
 
+For the CRISPR-Cas system, a good place to start is the [Wikipedia page](https://en.wikipedia.org/wiki/CRISPR)
+
 ## Example of genomic structure
 
 CRISPR-Cas systems have been classified in 6 different families :ref{doi=10.1038/s41579-019-0299-x}.