Perhaps you should try some spelling variations:
dinh viet » ninh viet, danh viet, trinh viet
viet cua » viec cua, viet ca, viet qua
te sach » toc sach
sach tu » sach thu, cach tu, sach ty
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
tu xang » ty xang, tu lang, tu quang
dac va » duc va, dat va, dai va
ma hoi » mai hoi, ma hoa, me hoi
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: te sach tu xang ((ma hoi) OR (xa hoi)). hieu ve cac ((dac va) or (day va)) dinh viet cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach tu xang ((ma hoi) OR (xa hoi)). hieu ve cac ((dac va) OR (day va)) dinh viet cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach tu xang ((ma hoi) OR (xa hoi)). hieu ve cac ((dac va) or (day va)) dinh viet cua tre*".