Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
hieu van » thien van, lieu va, hieu ve
khai cua » thai cua, hai cua, khi cua
dan khai » dang khai, van khai, dang khoi
hac tuc » thac toc, thai tuc
hieu va » lieu va, hieu qua
te sach » toc sach
tu nano » truc nano
tu nang » tru nang, tu nong, tu lang
tuc va » thuc va, truc va, tuc xa
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: te sach ((tu nang) or (tu nano)) xa hoi. ((hieu van) OR (hieu va)) hac tuc va dan khai cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((tu nang) OR (tu nano)) xa hoi. ((hieu van) OR (hieu va)) hac tuc va dan khai cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((tu nang) or (tu nano)) xa hoi. ((hieu van) OR (hieu va)) hac tuc va dan khai cua triet".
• Adding a wildcard symbol may retrieve word variants: te sach ((tu nang) or (tu nano)) xa hoi. ((hieu van) OR (hieu va)) hac tuc va dan khai cua triet*.