private void sheetComboBox_SelectedIndexChanged(object sender, EventArgs e)
        {
            ExcelBibliographicReader read = new ExcelBibliographicReader();

            try
            {
                // Make sure there is a filename and a sheet name
                if ((fileTextBox.Text.Length > 0) && (sheetComboBox.SelectedIndex >= 0))
                {
                    read.Sheet = sheetComboBox.Text;
                    read.Filename = fileTextBox.Text;

                    // Try reading data from the selected Excel Worksheet
                    if (!read.Check_Source())
                    {
                        MessageBox.Show("Unable to read the source sheet   ");
                        fileTextBox.Text = String.Empty;
                        filename = String.Empty;
                        sheetComboBox.Items.Clear();
                        sheetComboBox.Text = String.Empty;
                        sheetComboBox.Hide();
                        sheetLabel.Hide();
                        executeButton.Button_Enabled = false;
                    }
                    else
                    {
                        rawDataTbl = read.excelData;
                        columnname_to_input.Clear();
                        foreach (DataColumn thisColumn in rawDataTbl.Columns)
                        {
                            columnname_to_input[thisColumn.ColumnName.ToUpper().Trim()] = thisColumn.ColumnName.Trim();
                            thisColumn.ColumnName = thisColumn.ColumnName.ToUpper().Trim().Replace(" ","");
                        }

                        if (!Transform_Data())
                        {
                            fileTextBox.Text = String.Empty;
                            filename = String.Empty;
                            sheetComboBox.Items.Clear();
                            sheetComboBox.Text = String.Empty;
                            sheetComboBox.Hide();
                            sheetLabel.Hide();
                            executeButton.Button_Enabled = false;
                        }
                        else
                        {

                            // Check to see if multiple bibids loaded
                            string check_bib = transformedDataTbl.Rows[0][0].ToString().ToUpper();
                            bool multiple_bibs_in_table = transformedDataTbl.Rows.Cast<DataRow>().Any(thisRow => thisRow[0].ToString().ToUpper() != check_bib);

                            btnShowData.Location = new Point(239, 66);
                            btnShowData.Show();
                            if ((bibidLabel.Visible) || ( multiple_bibs_in_table ))
                                executeButton.Button_Enabled = true;
                        }

                    }

                    // Close the reader
                    read.Close();
                }
            }
            catch (Exception ex)
            {
                ErrorMessageBox.Show(ex.Message, "Unexpected Error", ex);
                fileTextBox.Text = String.Empty;
                filename = String.Empty;
                sheetComboBox.Items.Clear();
                sheetComboBox.Text = String.Empty;
                sheetComboBox.Hide();
                sheetLabel.Hide();
                executeButton.Button_Enabled = false;
            }
            finally
            {
                // Close the reader
                read.Close();
            }
        }
        private void Browse_Source()
        {
            fileTextBox.Text = String.Empty;
            filename = String.Empty;
            sheetComboBox.Items.Clear();
            sheetComboBox.Text = String.Empty;
            sheetComboBox.Hide();
            sheetLabel.Hide();
            btnShowData.Hide();
            executeButton.Button_Enabled = false;

            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                // Write the filename to the text box first
                fileTextBox.Text = openFileDialog1.FileName;
                filename = openFileDialog1.FileName;

                // Determine the filetype
                FileInfo fileInfo = new FileInfo(filename);
                string extension = fileInfo.Extension.ToUpper();
                if ((extension == ".XLS") || (extension == ".XLSX"))
                {
                    ExcelBibliographicReader read = new ExcelBibliographicReader();

                    try
                    {
                        // Try getting the worksheet names from the selected workbook
                        // Get the sheet names
                        read = new ExcelBibliographicReader();
                        List<string> tables = read.GetExcelSheetNames(openFileDialog1.FileName);

                        if (tables == null)
                        {
                            MessageBox.Show("Unable to read the source workbook.   ");
                            fileTextBox.Text = String.Empty;
                            filename = String.Empty;
                        }
                        else
                        {

                            // Populate the combo box
                            foreach (string thisSheetName in tables)
                                sheetComboBox.Items.Add(thisSheetName);

                            sheetComboBox.Show();
                            sheetLabel.Show();
                        }
                    }
                    catch (Exception ex)
                    {
                        ErrorMessageBox.Show(ex.Message, "Unexpected Error", ex);
                        fileTextBox.Text = String.Empty;
                        filename = String.Empty;
                    }
                    finally
                    {
                        // Close the reader
                        read.Close();
                    }
                    return;
                }

                // Check with CSV or TXT files
                if ((extension == ".CSV") || (extension == ".TXT"))
                {
                    // Create the splitter to use
                    string splitter = ",";
                    if (extension == ".TXT")
                        splitter = ",\t";
                    char[] splitter_chars = splitter.ToCharArray();

                    StreamReader text_reader = new StreamReader(filename);

                    try
                    {
                        string line = text_reader.ReadLine();
                        if (line != null)
                        {
                            string[] split = line.Split(splitter_chars);
                            int columns = 0;
                            rawDataTbl = new DataTable();
                            columnname_to_input.Clear();
                            foreach (string topRowSplit in split)
                            {
                                if (topRowSplit.Length > 0)
                                {
                                    columns++;
                                    rawDataTbl.Columns.Add(topRowSplit.ToUpper().Trim().Replace(" ", ""));
                                    columnname_to_input[topRowSplit.ToUpper().Trim().Replace(" ", "")] =
                                        topRowSplit.Trim();
                                }
                                else
                                {
                                    break;
                                }
                            }
                            line = text_reader.ReadLine();
                            while (line != null)
                            {
                                split = line.Split(splitter_chars);
                                DataRow newRow = rawDataTbl.NewRow();
                                for (int i = 0; (i < columns) && (i < split.Length); i++)
                                {
                                    newRow[i] = split[i];
                                }
                                rawDataTbl.Rows.Add(newRow);
                                line = text_reader.ReadLine();
                            }
                        }
                        btnShowData.Location = new Point(73,67);
                        btnShowData.Show();
                        if (bibidLabel.Visible)
                            executeButton.Button_Enabled = true;
                    }
                    catch
                    {
                        MessageBox.Show("Input text file is in improper format");
                        fileTextBox.Text = String.Empty;
                        filename = String.Empty;
                    }

                    text_reader.Close();
                    return;
                }

                // Type was invalid so just return
                fileTextBox.Text = String.Empty;
                filename = String.Empty;
            }
        }