Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh dai » hanh tai, hanh dao, vanh dai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
van dau » van dao, phan dau
truc va » thuc va, trung va
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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 ky nang ma hoi. hieu van dau ((truc va) OR (thuc vat)) hanh dai cua tre~.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. hieu van dau ((truc va) or (thuc vat)) hanh dai cua tre*.