Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
kho mang » kho tang, cho mang, pho mang
hieu van » hieu va, thien van, lieu va
su sach » vu sach
tinh vi » trinh vi, tinh voi, tinh va
va tinh » may tinh
cam tuc » cam xuc, cam tu, dam thuc
may hoi » may thoi, tay hoi, mai hoi
so sach » so sanh, bo sach, co sach
vi hoa » voi hoa, vi hoc, va hoa

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) or (so sach)) kho mang may hoi. hieu van ((cam tuc) OR (nam thuc)) va tinh vi hoa viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) kho mang may hoi. hieu van ((cam tuc) OR (nam thuc)) va tinh vi hoa viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sach)) kho mang may hoi. hieu van ((cam tuc) OR (nam thuc)) va tinh vi hoa viet".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sach)) kho mang may hoi. hieu van ((cam tuc) OR (nam thuc)) va tinh vi hoa viet*.