public AddBook()
        {
            InitializeComponent();
            AddPublication ap = new AddPublication();

            foreach (DataGridViewRow row in ap.dataGridView1.Rows)
            {
                comboBox1.Items.Add(row.Cells[0].Value.ToString());
            }
            AddBranch ab = new AddBranch();

            foreach (DataGridViewRow row in ab.dataGridView1.Rows)
            {
                comboBox2.Items.Add(row.Cells[0].Value.ToString());
            }
        }
        private void button1_Click(object sender, EventArgs e)
        {
            AddPublication a = new AddPublication();

            a.Show();
        }