Private Function LetzterSonntag(ByVal jahr As Integer, ByVal monat As _
      Integer) As Date
        Dim tage As Integer = DateTime.DaysInMonth(jahr, monat)
        For t As Integer = tage To (tage - 7) Step -1
            If New Date(jahr, monat, t).DayOfWeek = DayOfWeek.Sunday Then _
              Return New Date(jahr, monat, t)
        Next
    End Function