public function getBlockTypeSets()
    {
        $db = Loader::db();
        $list = array();
        $r = $db->Execute(
                'select btsID from BlockTypeSetBlockTypes where btID = ? order by displayOrder asc',
                array($this->getBlockTypeID()));
        while ($row = $r->FetchRow()) {
            $list[] = BlockTypeSet::getByID($row['btsID']);
        }
        $r->Close();

        return $list;
    }