Perhaps you should try some spelling variations:
viet dung » viet hung, viet huong, viet trung
vat dung » van dung, va dung, mat duong
sach ty » sach tu, sach thu, xach tay
qua cam » qua cham, qua cac, qua ca
cua tre » cua te, cuu tre, cua triet
cam tu » cam thu, nam tu, dam tu
co cua » con cua, ca cua, cong cua
x hoi » xa hoi, o hoi, x ho

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