Perhaps you should try some spelling variations:
hanh thai » nhanh thai, hinh thai, hanh tai
thai cua » than cua, tai cuc, tri cua
van hanh » van thanh, ban hanh, van anh
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
cua tre » cua te, cuu tre, cua triet
cac xuc » cam xuc, chat xuc, cac cuoc
hieu ve » hieu va, hieu van
tu san » thu san, tu ban, tu can
san ky » sang ky, van ky, dan ky
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, 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 san ky nang ((o hoi) or (o hai)). hieu ve ((cac xuc) OR (cac nuoc)) van hanh thai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu san ky nang ((o hoi) OR (o hai)). hieu ve ((cac xuc) OR (cac nuoc)) van hanh thai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu san ky nang ((o hoi) or (o hai)). hieu ve ((cac xuc) OR (cac nuoc)) van hanh thai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu san ky nang ((o hoi) or (o hai)). hieu ve ((cac xuc) OR (cac nuoc)) van hanh thai cua tre*.