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

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 ((hoc 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 ((hoc 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 ((hoc va) or (luc va)) hanh vi cua tre*.