Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
dinh vai » dinh van, dinh vi, dinh va
cam thuc » nam thuc, cam thu, can thuc
hieu van » hieu va, thien van, lieu va
lai hoi » dai hoi, lai hoa, lai roi
mai doi » moi doi, mai hoi, mai khoi
va dinh » van dinh, va kinh, va tinh
vai cua » dai cua, hai cua, lai cua
so sach » so sanh, bo sach, co sach
y nang » ky nang, ly nang, v 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 y nang ((mai doi) or (lai hoi)). hieu van ((cam thuc) or (am thuc)) va dinh 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 van ((cam thuc) OR (am thuc)) va dinh vai cua viet.
• Adding a wildcard symbol may retrieve word variants: so sach y nang ((mai doi) or (lai hoi)). hieu van ((cam thuc) or (am thuc)) va dinh vai cua viet*.