Perhaps you should try some spelling variations:
viet thanh » viet anh
tat thanh » tai thanh, ta thanh, tat thang
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
vai cua » dai cua, hai cua, lai cua
tu cach » tu cac
su sach » so sach, vu sach
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.

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (su sach)) ky nang x hoi. hieu van nam thuc ((viet thanh) or (tat thanh)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (su sach)) ky nang x hoi. hieu van nam thuc ((viet thanh) OR (tat thanh)) vai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (su sach)) ky nang x hoi. hieu van nam thuc ((viet thanh) or (tat thanh)) vai cua tre*.