Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, co sach
sach ty » sach y, sach tu, sach thu
van hac » van hoc, van ha, van hai
lang xa » lang ha, dang xay, lang van
xang xa » mang xa, ang xa, dang xay
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, xac va
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: so sach ty ((xang xa) OR (lang xa)) hoi. hieu van hac ((xuc va) or (luc va)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty ((xang xa) OR (lang xa)) hoi. hieu van hac ((xuc va) OR (luc va)) hanh vi cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty ((xang xa) OR (lang xa)) hoi. hieu van hac ((xuc va) or (luc va)) hanh vi cua tre*".