diff --git a/Synology-NAS-Guide.md b/Synology-NAS-Guide.md
index a7bf086d..113bf61a 100644
--- a/Synology-NAS-Guide.md
+++ b/Synology-NAS-Guide.md
@@ -38,7 +38,7 @@ export CF_Token="MY_SECRET_TOKEN_SUCH_SECRET"
 export CF_Email="myemail@example.com"
 ```
 
-In case you use another DNS service, check the `dnsapi` directory. Instructions for many DNS providers are already included. You can also find instructions on how to add another DNS service there, although that requires some software development skills.
+In case you use another DNS service, check the `dnsapi` directory and [DNS API guide](https://github.com/acmesh-official/acme.sh/wiki/dnsapi). Instructions for many DNS providers are already included. You can also find instructions on how to add another DNS service there, although that requires some software development skills.
 
 ## Creating the certificate
 Now it's time to create the certificate for your domain: