assertEquals("Sheet3", _workbook1.getSheetName(2));
assertEquals(0, _workbook2.getSheetIndex("Sheet 1"));
assertEquals(1, _workbook2.getSheetIndex("Sheet2"));
assertEquals(2, _workbook2.getSheetIndex("Sheet3"));
_books = new BookSeriesImpl(new Book[] {(Book) _workbook1, (Book) _workbook2});
}