Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
cam thuc » am thuc, nam thuc, cam thu
hieu van » hieu va, thien van, lieu va
vai cua » dai cua, hai cua, lai cua
va kinh » va tinh, qua kinh
va danh » va dinh, va dan, va hanh
so sach » so sanh, bo sach, co sach
mai doi » moi doi, mai hoi, mai khoi
lai hoi » dai hoi, lai hoa, lai roi
van cam » van nam, van lam, van cau
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang

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 v nang ((mai doi) or (lai hoi)). hieu van cam thuc ((va danh) or (va kinh)) vai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach v nang ((mai doi) OR (lai hoi)). hieu van cam thuc ((va danh) OR (va kinh)) vai cua viet.
• Adding a wildcard symbol may retrieve word variants: so sach v nang ((mai doi) or (lai hoi)). hieu van cam thuc ((va danh) or (va kinh)) vai cua viet*.