Perhaps you should try some spelling variations:
"su sach ngonh ky thuat co hoc" » "su sach ngon ky thuat co hoc", "su sach ngan ky thuat co hoc", "su sach nganh ky thuat co hoc", "su sach ngonh ky thuat do hoc", "su sach ngonh ky thuat o hoc", "so sach ngonh ky thuat co hoc", "vu sach ngonh ky thuat co hoc"
"so sanh ngoc giai thuat hoa hoc" » "so sanh ngoc giai thoai hoa hoc", "so sanh ngoc giai khat hoa hoc", "so sanh ngoc gian thua hoa hoc", "so anh ngoc giai thuat hoa hoc", "so thanh ngoc giai thuat hoa hoc", "so van ngoc giai thuat hoa hoc", "so sanh nuoc giai thuat hoa hoc", "so sanh ngoi giai thuat hoa hoc", "so sanh ngoc giang thuat hoa hoc", "so sanh ngoc giai thuat toan hoc", "so sanh ngoc giai thuyet hoa hoc", "so sanh ngoc giai thuat do hoc", "do sanh ngoc giai thuat hoa 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 ngonh ky thuat co hoc") or ("so sanh ngoc giai thuat hoa hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("su sach ngonh ky thuat co hoc") OR ("so sanh ngoc giai thuat hoa hoc")).
• Removing quotes may allow a broader search: (( su sach ngonh ky thuat co hoc ) or ( so sanh ngoc giai thuat hoa hoc )).
• Adding a wildcard symbol may retrieve word variants: (("su sach ngonh ky thuat co hoc") or ("so sanh ngoc giai thuat hoa hoc"))*.