Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam tu
thanh vi » hanh vi, thanh va, thanh ve
su triet » su viet, su tien, ve triet
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
x hoi » xa hoi, o hoi, x ho
khach » khac, khanh

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: vay khach y nang x hoi. hieu van ((nam thuc) OR (nam thu)) ban thanh vi ((cua tre) or (su triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vay khach y nang x hoi. hieu van ((nam thuc) OR (nam thu)) ban thanh vi ((cua tre) OR (su triet))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vay khach y nang x hoi. hieu van ((nam thuc) OR (nam thu)) ban thanh vi ((cua tre) or (su triet))*".