Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
cam thuc » am thuc, cam thu, can thuc
danh hai » dang hai, lanh hai, manh hai
nam thuc » nam thuoc, am thuc, nam thu
hai cua » thai cua, dai cua, hoi cua
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
hieu ve » hieu va, hieu van
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 ve ((cam thuc) OR (nam thuc)) va danh hai 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 ve ((cam thuc) OR (nam thuc)) va danh hai cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach v nang ((mai doi) or (lai hoi)). hieu ve ((cam thuc) OR (nam thuc)) va danh hai cua viet".
• Adding a wildcard symbol may retrieve word variants: so sach v nang ((mai doi) or (lai hoi)). hieu ve ((cam thuc) OR (nam thuc)) va danh hai cua viet*.