Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
hieu van » hieu va, thien van, lieu va
thai cua » than cua, tai cuc, tri cua
van hanh » ban hanh, van anh, van ban
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va
sac ky » cac ky, sai ky
nang o » nang co, nang ho, nang ro
tu sac » tu sach, tu cac, tu san
o lai » o lao

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang o lai. ((hieu ve) OR (hieu van)) cac du ((van hanh) OR (van thanh)) thai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky nang o lai. ((hieu ve) or (hieu van)) cac du ((van hanh) OR (van thanh)) thai cua tre~".
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang o lai. ((hieu ve) or (hieu van)) cac du ((van hanh) OR (van thanh)) thai cua tre*.