Perhaps you should try some spelling variations:
vat dung » van dung, va dung, viet dung
dung doi » huong doi, dung tai, dung co
sach ty » sach tu, sach thu, xach tay
qua cam » qua cham, qua cac, qua ca
doi cua » dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
cam tu » cam thu, nam tu, dam tu
tu vat » tu va, tu van, tu bat
x hoi » o hoi, x ho, 5 hoi

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ty) or (sach y)) nang ((x hoi) OR (xa hoi)). hieu qua cam tu vat dung doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach y)) nang ((x hoi) OR (xa hoi)). hieu qua cam tu vat dung doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) or (sach y)) nang ((x hoi) OR (xa hoi)). hieu qua cam tu vat dung doi cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach y)) nang ((x hoi) OR (xa hoi)). hieu qua cam tu vat dung doi cua tre*.