Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
vanh dai » van dai, vanh tai, lanh dao
nay thuc » nam thuc, cay thuc, day thuc
va vanh » va van, va danh, va hanh
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
su sach » so sach, vu sach
va nay » va ngay, va cay
o hoi » co hoi, o hoc, o hoa
o hai » co hai, so hai, o lai

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: ((thu sach) OR (su sach)) ky nang ((o hoi) OR (o hai)). hieu va nay thuc va vanh dai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (su sach)) ky nang ((o hoi) OR (o hai)). hieu va nay thuc va vanh dai cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (su sach)) ky nang ((o hoi) OR (o hai)). hieu va nay thuc va vanh dai cua tre*.