Perhaps you should try some spelling variations:
tinh viet » trinh viet, ninh viet, dinh viet
viet cua » viec cua, viet ca, viet qua
te sach » toc sach
hieu va » lieu va, hieu qua
va tinh » may tinh
cac dac » cac dan, cac dai, cac bac
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ty sang » ty hang, duy sang, thu sang
dac va » duc va, day va, dat va

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 ((ty sang) or (ty xang)) mai hoi. ((hieu ve) OR (hieu va)) cac dac va tinh viet cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ty sang) OR (ty xang)) mai hoi. ((hieu ve) OR (hieu va)) cac dac va tinh viet cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ty sang) or (ty xang)) mai hoi. ((hieu ve) OR (hieu va)) cac dac va tinh viet cua tre*".