final EmployeeSalaryDO first = list.get(0);
final int year = first.getYear();
final int month = first.getMonth();
final DayHolder buchungsdatum = new DayHolder();
buchungsdatum.setDate(year, month, 1);
final MonthHolder monthHolder = new MonthHolder(buchungsdatum.getDate());
final BigDecimal numberOfWorkingDays = monthHolder.getNumberOfWorkingDays();
buchungsdatum.setEndOfMonth();
final String sheetTitle = DateHelper.formatMonth(year, month);
final ExportSheet sheet = xls.addSheet(sheetTitle);
sheet.createFreezePane(0, 1);