Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
thanh vai » thanh hai, thanh van, thanh tai
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
tu cach » tu cac
su sach » so sach, vu sach
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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 o hoi. hieu van nam thuc vat thanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (su sach)) ky nang o hoi. hieu van nam thuc vat thanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (su sach)) ky nang o hoi. hieu van nam thuc vat thanh vai cua tre*.