Perhaps you should try some spelling variations:
thien van » thi van
hieu van » hieu va, lieu va, hieu ve
cuu ban » cuu van, cua ban, cuu nang
cuu san » cuu van, cua san, cuu nang
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
vi cua » vai cua, di cua
o hai » co hai, so hai, o lai

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu cac ky nang o hai. ((hieu van) or (thien van)) cap ((cuu ban) OR (cuu san)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cac ky nang o hai. ((hieu van) OR (thien van)) cap ((cuu ban) OR (cuu san)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu cac ky nang o hai. ((hieu van) or (thien van)) cap ((cuu ban) OR (cuu san)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu cac ky nang o hai. ((hieu van) or (thien van)) cap ((cuu ban) OR (cuu san)) hanh vi cua tre*.