Koha SQL Command List of items added in between two dates

SELECT sum(items.barcode), items.barcode,items.dateaccessioned,biblio.title,biblio.author FROM items LEFT JOIN biblioitems on (items.biblioitemnumber=biblioitems.biblioitemnumber) LEFT JOIN biblio on (biblioitems.biblionumber=biblio.biblionumber)   WHERE biblio.datecreated >= 'yyyy-mm-dd' AND biblio.datecreated <= 'yyyy-mm-dd' GROUP BY items.barcode ORDER BY items.dateaccessioned asc

  Change the two dates as per the order like ( yyyy-mm-dd 2013-01-01 to  2013-06-27)