Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
cac tuc » cac toc, cac tu, cac tac
sach ky » sac ky, sach y, sach ty
hieu ve » hieu van
hieu va » lieu va, hieu qua
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
tuc va » thuc va, truc va, tuc xa
dan vi » doan vi, don vi, gan vi
dan va » doan va, dan ca, ban 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 sang ma hoi. ((hieu ve) or (hieu va)) cac tuc va ((dan vi) OR (dan va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang ma hoi. ((hieu ve) OR (hieu va)) cac tuc va ((dan vi) OR (dan va)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky sang ma hoi. ((hieu ve) or (hieu va)) cac tuc va ((dan vi) OR (dan va)) cua tre*".