Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
thanh dai » thanh hai, thanh tai, thanh dat
hieu van » thien van, lieu va, hieu ve
nam thuc » nam thuoc, am thuc, nam thu
tu cach » tu cac
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
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) OR (hieu va)) nam thuc vat thanh dai 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) OR (hieu va)) nam thuc vat thanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (su sach)) ky nang x hoi. ((hieu van) OR (hieu va)) nam thuc vat thanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (su sach)) ky nang x hoi. ((hieu van) OR (hieu va)) nam thuc vat thanh dai cua tre*.