Perhaps you should try some spelling variations:
thanh toan » thanh hoa, thanh san, tinh toan
hau treo » cau treo, cau theo, dau tren
toan hau » toan cau, toan dau, toan ham
thuc day » thuc dan, thuc vat
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
va nam » van nam, ha nam, va nay
o hoc » co hoc, mo hoc, so hoc
o hoi » co hoi, o hai, o hoa

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 (o hoc)). hieu va nam ((thuc va) OR (thuc day)) thanh toan hau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang ((o hoi) OR (o hoc)). hieu va nam ((thuc va) OR (thuc day)) thanh toan hau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky nang ((o hoi) or (o hoc)). hieu va nam ((thuc va) OR (thuc day)) thanh toan hau treo".
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang ((o hoi) or (o hoc)). hieu va nam ((thuc va) OR (thuc day)) thanh toan hau treo*.