Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
vai cua » dai cua, hai cua, lai cua
dan vai » dan va, dan tai, dan vat
chu duc » thu duc, chua duoc, cuu duoc
hieu va » lieu va, hieu qua
so sach » so sanh, bo sach, co sach
le lang » le tang, le dang, le xang
lo lang » o lang, so lang, hoa lang
cua tre » cua te, cuu tre, cua triet
va dan » ca dan, va dao, va dau

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 ((lo lang) OR (le lang)) xa hoi. ((hieu van) or (hieu va)) chu duc va dan vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((lo lang) OR (le lang)) xa hoi. ((hieu van) OR (hieu va)) chu duc va dan vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((lo lang) OR (le lang)) xa hoi. ((hieu van) or (hieu va)) chu duc va dan vai cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((lo lang) OR (le lang)) xa hoi. ((hieu van) or (hieu va)) chu duc va dan vai cua tre*.