Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cua tre » cuu tre, cua triet, dua tren
cac tho » cac thoi, cac tro, cac thu
hieu va » lieu va, hieu qua
hieu ve » hieu van
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
tho va » tho van, tao va, tho ca
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
cua te » cua tu

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 ma hoa. ((hieu ve) or (hieu va)) cac tho va dan vi ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky tang ma hoa. ((hieu ve) OR (hieu va)) cac tho va dan vi ((cua tre) OR (cua te))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky tang ma hoa. ((hieu ve) or (hieu va)) cac tho va dan vi ((cua tre) OR (cua te))*".