private void btnPhieuXuat_Click(object sender, EventArgs e)
{
frmPhieuXuat frm = new frmPhieuXuat();
frm.Show();
}
private void phiếuXuấtToolStripMenuItem_Click_1(object sender, EventArgs e)
{
frmPhieuXuat frm = new frmPhieuXuat();
frm.ShowDialog();
}