private void right_btn_Click(object sender, EventArgs e)
 {
     rightForm      = new AmTietForm();
     rightForm.Text = "Right AmTiet";
     rightForm.SelectAmTietHandler += SelectAmTietRight;
     rightForm.Show();
 }
 private void left_btn_Click(object sender, EventArgs e)
 {
     leftForm      = new AmTietForm();
     leftForm.Text = "Left AmTiet";
     leftForm.SelectAmTietHandler += SelectAmTietLeft;
     leftForm.Show();
 }
 private void refWord_btn_Click(object sender, EventArgs e)
 {
     referForm      = new AmTietForm();
     referForm.Text = "Refer AmTiet";
     referForm.SelectAmTietHandler += SelectReferAmTiet;
     referForm.Show();
 }