Perhaps you should try some spelling variations:
"su sach ngon ky thuat co hoc" » "su sach ngan ky thuat co hoc", "su danh ngon ky thuat co hoc", "su canh ngon ky thuat co hoc", "su sach ngon ky thuat do hoc", "su sach ngon ky thuat o hoc", "so sach ngon ky thuat co hoc", "vu sach ngon ky thuat co hoc", "su sach ngon keo thuat co hoc"
"so danh nhan hay thuat toan hoc" » "so doanh nhan hay thuat toan hoc", "so thanh nhan hay thuat toan hoc", "so benh nhan hay thuat toan hoc", "so danh nhan phau thuat toan hoc", "so danh nhan my thuat toan hoc", "so danh nhan va thuat toan hoc", "so danh nhan ha thuat toan hoc", "so danh ngan hay thuat toan hoc", "so danh nhan kham thuat toan hoc", "so danh nhan hay thuat toan khoa", "so danh nhan hay thuat van hoc", "so danh nhan hay thuat hoa hoc", "do danh nhan hay thuat toan hoc", "so sanh nhan hay thuat toan hoc", "so dan nhan hay thuat toan hoc"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("su sach ngon ky thuat co hoc") or ("so danh nhan hay thuat toan hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("su sach ngon ky thuat co hoc") OR ("so danh nhan hay thuat toan hoc")).
• Removing quotes may allow a broader search: (( su sach ngon ky thuat co hoc ) or ( so danh nhan hay thuat toan hoc )).
• Adding a wildcard symbol may retrieve word variants: (("su sach ngon ky thuat co hoc") or ("so danh nhan hay thuat toan hoc"))*.