private void thToolStripMenuItem_Click(object sender, EventArgs e)
        {
            FormLapPhieuThu f = new FormLapPhieuThu();

            f.Show();
        }
        private void button4_Click(object sender, EventArgs e)
        {
            FormLapPhieuThu f = new FormLapPhieuThu();

            f.Show();
        }