Perhaps you should try some spelling variations:
doan thi » dan thi, doanh tai, hoang thi
lang van » dang van, tang van, hoang van
tu sach » thu sach, su sach, te sach
cac thu » cach thuc, cac thoi
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
lang xa » lang ha, dang xay
thu va » thuc va, thue va, tu va
dan vi » doan vi, don vi, dan va
ve cac » va cac, vien cac

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 ((lang xa) OR (lang van)) hoi. hieu ve cac thu va ((dan vi) or (doan thi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((lang xa) OR (lang van)) hoi. hieu ve cac thu va ((dan vi) OR (doan thi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((lang xa) OR (lang van)) hoi. hieu ve cac thu va ((dan vi) or (doan thi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((lang xa) OR (lang van)) hoi. hieu ve cac thu va ((dan vi) or (doan thi)) cua tre*.