Private Function GetMonthDays(ByVal Mon As Byte, ByVal Jahr As Integer) As Byte
    GetMonthDays = 31
    Select Case Mon
       Case 2
          GetMonthDays = 28
          If Jahr Mod 4 = 0 Then GetMonthDays = 29
       Case Is < 7
          If Mon Mod 2 = 0 Then GetMonthDays = 30
       Case Is > 7
          If Mon Mod 2 <> 0 Then GetMonthDays = 30
    End Select
End Function

Private Function GetFirstWeekDay(ByVal Mon As Byte, ByVal Jahr As Integer) As _
  String
   GetFirstWeekDay = WeekdayName(Weekday(DateSerial(Jahr, Mon, 1), vbMonday), _
   vbuseSystemDayofWeekday)
End Function