Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
tang mai » tang ma, tang tai, lang mai
cuu tre » cua tre, cau treo
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
hieu ve » hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ky tang » ky nang, ky dang, kho tang
hieu va » lieu va, hieu qua
tro va » tao va, tho va, tro ba
va dao » ca dao
dao vi » dao voi, dao ve, dao va

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 ky tang mai hoi. ((hieu ve) or (hieu va)) cac tro va dao vi ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky tang mai hoi. ((hieu ve) OR (hieu va)) cac tro va dao vi ((cuu tre) OR (cau tren))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky tang mai hoi. ((hieu ve) or (hieu va)) cac tro va dao vi ((cuu tre) OR (cau tren))*".