diff --git a/rules/gsuite_reports_rules/gsuite_drive_external_share.yml b/rules/gsuite_reports_rules/gsuite_drive_external_share.yml
index 4fd8368d8..39d87bdef 100644
--- a/rules/gsuite_reports_rules/gsuite_drive_external_share.yml
+++ b/rules/gsuite_reports_rules/gsuite_drive_external_share.yml
@@ -18,6 +18,7 @@ Description: An employee shared a sensitive file externally with another organiz
 Runbook: >
   Contact the employee who made the share and make sure they redact the access.
   If the share was legitimate, add to the EXCEPTION_PATTERNS in the detection.
+Reference: https://developers.google.com/admin-sdk/reports/v1/appendix/usage/user/drive#visibility-parameters
 Tests:
   -
     Name: Dangerous Share of Known Document with a Missing User