public Range getColumns() {
final Ref ref = getRefs().iterator().next();
final Worksheet sheet = BookHelper.getSheet(_sheet, ref.getOwnerSheet());
final int col1 = ref.getLeftCol();
final int col2 = ref.getRightCol();
final Book book = (Book) sheet.getWorkbook();
return new RangeImpl(0, col1, book.getSpreadsheetVersion().getLastRowIndex(), col2, sheet, sheet);
}