Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thanh ve » hanh ve, thanh va, thanh vien
da thanh » dao thanh, dat thanh, dam thanh
cac tac » cac toc, cac bac, cac dac
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
xang co » nang co, lang co, tang co
so sach » so sanh, bo sach, co sach
hieu ve » hieu van
co hai » co dai, co hoi, o hai
ve su » va su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (so sach)) ty xang co hai. ((hieu ve) or (hieu va)) cac tac da thanh ve su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (so sach)) ty xang co hai. ((hieu ve) OR (hieu va)) cac tac da thanh ve su triet.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (so sach)) ty xang co hai. ((hieu ve) or (hieu va)) cac tac da thanh ve su triet*.