ISBN is not the only way to verify a reference. For instance, references I used in Ban Borić article are recent scans by Google Scanning project of most notable Hungarian historian researchers of Hungary's royalty. Sorry they didn't have ISBN system invented 16th-19th century. You have just demonstrated how rude you are by reverting my edits of Ban Borić article while the editing was still in progress. You also did it (again, as in here for the House of Berislavić) without bothering to discuss it in Talk. If you are the owner of Wikimedia Foundation please let me know so that I don't bother any more.