Perhaps you should try some spelling variations:
thien van » thi van
thanh tra » thanh toan, thanh hoa
ban thanh » ban hanh, ban hang
hieu van » hieu va, lieu va, hieu ve
tu sach » thu sach, su sach, te sach
tra cua » trau cua, trua cua, tra cuu
duc ban » duc tan, duc van, dua ban
lam duc » lam duoc, pham duc, nam duoc
cua tre » cua te, cuu tre, cua triet
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: tu sach y nang ((x hoi) OR (o hoi)). ((hieu van) or (thien van)) lam duc ban thanh tra cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((x hoi) OR (o hoi)). ((hieu van) OR (thien van)) lam duc ban thanh tra cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((x hoi) OR (o hoi)). ((hieu van) or (thien van)) lam duc ban thanh tra cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((x hoi) OR (o hoi)). ((hieu van) or (thien van)) lam duc ban thanh tra cua tre*.