Корректная обработка закрытия Excel

  private static string[] GetCollectionsFromExcel(string fileName)
        {
           
            Application excapp;
            List<string> collectionRecordsList = new List<string>();
             
            try 
            { excapp = new Application(); 
             Workbooks wbs  = excapp.Workbooks;
             Workbook wb = wbs.Open(fileName, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
             _Worksheet ws  = (_Worksheet)wb.Sheets["Mar14"];
            Range range = ws.UsedRange;
            for (int i = 2; i <= range.Rows.Count; i++)
            {
                if ((ws.Cells[i, 1] as Range).Value2.ToString() == "")
                    continue;
                collectionRecordsList.Add((ws.Cells[i, 1] as Range).Value2 + "," + (ws.Cells[i, 2] as Range).Value2 + "," + (ws.Cells[i, 3] as Range).Value2 + "," + (ws.Cells[i, 4] as Range).Value2 + "," + (ws.Cells[i, 5] as Range).Value2);
            }
               
            
            DisposeExcelObjects(ref excapp, ref  wbs, ref wb, ref ws);
            }
            catch (Exception ex) {  ERROR_MESSAGE += "\n" + ex.ToString(); }
            return collectionRecordsList.ToArray();
        }

private void DisposeExcelObjects(ref Application excapp, ref Workbooks wbs, ref Workbook wb, ref _Worksheet ws)
{
    //_Worksheet  - это какой-то пользовательский класс, наследующий Worksheet. Надеюсь, Dispose предусмотрен
    ws.Dispose();
    wb.Close(false);
    wbs=null;//что здесь собирается ТС делать с коллекцией не знаю
    excapp.Quit();
}

private void DisposeExcelObjects(Application excapp = null, Workbooks wbs = null, Workbook wb = null, _Worksheet ws = null)
{
    if(ws!=null) ws.Dispose();
   if(wb!=null) wb.Close(false);
    if(wbs!=null)wbs=null;
    if(excapp!=null)excapp.Quit();
}