Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
cam thuc » am thuc, nam thuc, cam thu
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va hanh, dia danh
so sach » so sanh, bo sach, co sach
hieu ve » hieu va, hieu van
lai hoi » dai hoi, lai hoa, lai roi
mai doi » moi doi, mai hoi, mai khoi
y nang » ky nang, ly nang, v nang
va dan » ca dan, va dao, va dau
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y nang ((mai doi) or (lai hoi)). hieu ve cam thuc ((va danh) OR (va dan)) vai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y nang ((mai doi) OR (lai hoi)). hieu ve cam thuc ((va danh) OR (va dan)) vai cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y nang ((mai doi) or (lai hoi)). hieu ve cam thuc ((va danh) OR (va dan)) vai cua viet".
• Adding a wildcard symbol may retrieve word variants: so sach y nang ((mai doi) or (lai hoi)). hieu ve cam thuc ((va danh) OR (va dan)) vai cua viet*.