Perhaps you should try some spelling variations:
doan thi » dan thi, doanh tai, hoang thi
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
doan vi » doan va, don vi, doan van
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
cac tu » cac thu, cach tu, cac du
ve cac » va cac, vien cac
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 lang xa hoi. hieu ve cac tu va ((dan va) or (((doan vi) OR (doan thi)))) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang xa hoi. hieu ve cac tu va ((dan va) OR (((doan vi) OR (doan thi)))) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky lang xa hoi. hieu ve cac tu va ((dan va) or (((doan vi) OR (doan thi)))) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang xa hoi. hieu ve cac tu va ((dan va) or (((doan vi) OR (doan thi)))) cua tre*.