Function ISFILE(ϸ As String) As Boolean

    Dim  As Workbook
    Dim Ȯ As Boolean

    Ȯ = False

    On Error Resume Next
        
        Set  = Workbooks(ϸ)
        
        If Err.Number = 0 Then Ȯ = True
        
    ISFILE = Ȯ

End Function