private void button2_Click(object sender, EventArgs e)
{
frmLapPhieuNhapSach.maSach = layMaSach;
layTheLoai = TheLoai_BUS.LayTenTheLoai(int.Parse(layTheLoai));
frmLapPhieuNhapSach.theloai = layTheLoai;
frmLapPhieuNhapSach.tensach = layTenSach;
frmHoaDonBanSach.maSach = layMaSach;
frmHoaDonBanSach.tenSach = layTenSach;
frmHoaDonBanSach.donGiaBan = layDonGiaBan;
this.Close();
}