Perhaps you should try some spelling variations:
thanh van » thanh san, thanh toan, thanh phan
dan thanh » dang thanh, danh thanh, ban thanh
hau treo » cau treo, cau theo, dau tren
nam hoi » nam khoa
van hau » van ha, van hai, van dau
nam hoc » nam moc, am hoc, nam ho
hieu va » lieu va, hieu qua
sac ky » cac ky, sai ky
tu sac » tu sach, tu cac, tu san
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 sac ky nang ((o hoi) or (co hoc)). hieu va ((nam hoc) OR (nam hoi)) dan thanh van hau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang ((o hoi) OR (co hoc)). hieu va ((nam hoc) OR (nam hoi)) dan thanh van hau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky nang ((o hoi) or (co hoc)). hieu va ((nam hoc) OR (nam hoi)) dan thanh van hau treo".
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang ((o hoi) or (co hoc)). hieu va ((nam hoc) OR (nam hoi)) dan thanh van hau treo*.