Perhaps you should try some spelling variations:
tang thanh » dang thanh, trung thanh, hoang thanh
thanh van » thanh san, thanh toan, thanh phan
luc tang » tuc tang, luc sang, duc tang
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, te sach, tu cach
van cua » vang cua, ban cua, dan cua
ban luc » van luc, bao luc, nang luc
cua tre » cua te, cuu tre, cua triet
su sach » so sach, vu sach
y nang » ky nang, ly nang, v nang
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: ((tu sach) or (su sach)) y nang ((x hoi) or (o hoi)). hieu van ban luc tang thanh van cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) y nang ((x hoi) OR (o hoi)). hieu van ban luc tang thanh van cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) y nang ((x hoi) or (o hoi)). hieu van ban luc tang thanh van cua tre*.