diff --git a/.envrc.sample b/.envrc.sample
index ef65fcc..c01c2a7 100644
--- a/.envrc.sample
+++ b/.envrc.sample
@@ -7,7 +7,7 @@ export LETS_ENCRYPT_ENV=production
 export DB_ROOT_PASSWORD_VERSION=v1
 export ENTRYPOINT_CONF_VERSION=v1
 
-# OAuth
+# OAuth, see https://hackmd.io/@codimd/codimd-generic-oauth-2
 
 #export CMD_OAUTH2_PROVIDERNAME="Keycloak"
 #export CMD_OAUTH2_BASEURL="https://keycloak.example.com/realms/realmname/protocol/openid-connect/"