Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cuu tre, cua triet
van cac » van hac, van cau, van bac
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
can ky » van ky, dan ky, ban ky
loc va » hoc va
luc va » duc va, tuc va
vi cua » vai cua, di cua
tu can » tu ban, tu cac, thu canh

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

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