Perhaps you should try some spelling variations:
sach tay » sach hay, sach nay, sach tai
xach tay » canh tay
vat dung » van dung, va dung, viet dung
van hoi » van hoc, van hoe, van loi
hieu va » lieu va, hieu qua
cac tac » cac toc, cac bac, cac dac
tac vat » tap vat, tac va, tao vat
cuc te » cua te, cuc thue, cuc tieu

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: tu ((sach tay) OR (xach tay)) lang ((van hoi) OR (van hoa)). hieu va cac tac vat dung tai cuc te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach tay) OR (xach tay)) lang ((van hoi) or (van hoa)). hieu va cac tac vat dung tai cuc te~".
• Adding a wildcard symbol may retrieve word variants: tu ((sach tay) OR (xach tay)) lang ((van hoi) or (van hoa)). hieu va cac tac vat dung tai cuc te*.