Approval.

frontend/pt/sources.json

@@ -65,6 +65,9 @@
         "license_explica": "The license of the source or the digitized version thereof.",
         "source_fulltext": "Full text",
         "mentioned_places": "Mentioned places",
-        "covers_timespan": "Covers timespan"
+        "covers_timespan": "Covers timespan",
+        "editor": "Editor",
+        "booktitle": "Book title",
+        "isbn": "ISBN"
     }
 }