Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh van » thanh san, thanh toan, thanh phan
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nam duc » nam duoc, pham duc, nam thuc
duc ban » duc tan, duc van, dua ban
van cua » vang cua, ban cua, dan cua
cua tre » cua te, cuu tre, cua triet
x hoi » xa hoi, x ho, 5 hoi
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: su sach ky nang ((x hoi) or (o hoi)). hieu van nam duc ban thanh van cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((x hoi) OR (o hoi)). hieu van nam duc ban thanh van cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((x hoi) or (o hoi)). hieu van nam duc ban thanh van cua tre*.