Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty dang » ty xang, ky dang, ty hang
dang ma » dang mau, dang mam, dang mat
hieu ve » hieu van
hieu va » lieu va, hieu qua
ca doan » ca dan, chan doan, cac doanh
doan vi » doan va, don vi, doan thi
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
tro ca » tro cua, tro cap, tho ca
vi cua » vai cua, di cua

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 ty dang ma hoi. ((hieu ve) or (hieu va)) cac tro ca doan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty dang ma hoi. ((hieu ve) OR (hieu va)) cac tro ca doan vi cua tre*.