Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, hieu ve
cam thuc » am thuc, nam thuc, cam thu
vat dung » van dung, va dung, viet dung
dung doi » huong doi, dung tai, dung co
so sach » so sanh, bo sach, co sach
va nang » van nang, da nang, cam nang
doi cua » dai cua, hoi cua
v nang » vu nang, van nang, voi nang
cua tu » cua tuc, cua su, cua cu

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) OR (va nang)) xa hoi. ((hieu van) or (lieu va)) cam thuc vat dung doi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((v nang) OR (va nang)) xa hoi. ((hieu van) OR (lieu va)) cam thuc vat dung doi cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((v nang) OR (va nang)) xa hoi. ((hieu van) or (lieu va)) cam thuc vat dung doi cua tu".
• Adding a wildcard symbol may retrieve word variants: so sach ((v nang) OR (va nang)) xa hoi. ((hieu van) or (lieu va)) cam thuc vat dung doi cua tu*.