Public Function Datum_KW(ByVal dblKW As Double, ByVal iJahr As Integer, _
      ByVal strTag As String) As Date
 
        Dim iVBTag As Integer
        Dim lday As Long
        Dim vdate As DateTime = DateSerial(iJahr, 1, 1)
        Dim dblAddTage As Double
 
        'Tag ermitteln
        Select Case strTag
            Case "Montag" : iVBTag = 0
            Case "Dienstag" : iVBTag = 1
            Case "Mittwoch" : iVBTag = 2
            Case "Donnerstag" : iVBTag = 3
            Case "Freitag" : iVBTag = 4
            Case "Samstag" : iVBTag = 5
            Case "Sonnabend" : iVBTag = 5
            Case "Sonntag" : iVBTag = 6
        End Select
 
        For lday = 1 To 7
            If vdate.DayOfWeek = DayOfWeek.Thursday Then
                vdate = vdate.AddDays(-3)
                Exit For
            End If
            vdate = vdate.AddDays(1)
        Next
 
        dblAddTage = (7 * (dblKW - 1)) + iVBTag
        vdate.AddDays(dblAddTage)
        Exit Function
 
    End Function