Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
vat dung » va dung, viet dung, mat duong
van dung » van dong, xay dung, tin dung
sach ty » sach tu, sach thu, xach tay
qua nam » quan nam, cua nam, quang nam
doi cua » dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
x hoi » xa hoi, o hoi, x ho

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach y)) nang x hoi. hieu qua nam thuc ((vat dung) OR (van 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. hieu qua nam thuc ((vat dung) OR (van dung)) doi cua tre~".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach y)) nang x hoi. hieu qua nam thuc ((vat dung) OR (van dung)) doi cua tre*.