Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
vu khanh » vu thanh, van khanh, duy khanh
thanh ve » hanh ve, thanh va, thanh vien
thuc ban » thuoc ban, thuc dan, thu ban
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
khanh y » khanh ly, hanh y, khanh v
cua tre » cua te, cuu tre, cua triet
su viet » so viet
y nang » ky nang, ly nang, v nang
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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

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