diff --git a/ent/previewcardhistory.go b/ent/previewcardhistory.go
index dbd8b02..7abdfd1 100644
--- a/ent/previewcardhistory.go
+++ b/ent/previewcardhistory.go
@@ -4,6 +4,8 @@ import (
 	"sourcecode.social/reiver/go-opt"
 )
 
+// See:
+// https://docs.joinmastodon.org/entities/PreviewCard/#history
 type PreviewCardHistory struct {
 	Day      opt.Optional[string] `json:"day"`
 	Accounts opt.Optional[string] `json:"accounts"`