public IActionResult Index()
{
ViewBag.countsach = sachRepository.CountSach();
ViewBag.counttheloai = theLoaiRepository.CountTheLoai();
ViewBag.counttacgia = tacGiaRepository.CountTacGia();
ViewBag.countnxb = nhaXuatBanRepository.CountNXB();
ViewBag.countdocgia = docGiaRepository.CountDocGia();
return(View());
}