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