Perhaps you should try some spelling variations:
thieu van » thien van, thi van, hieu va
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, co sach
xay hoi » xa hoi, cay phoi, gay thoi
tay hoi » tay ho, tao hoi, tay thai
van cac » van hac, van cau, van bac
cua tre » cua te, cuu tre, cua triet
xac va » tac va, ac va, bac va
vi cua » vai cua, di cua

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: so sach thieu van ((xay hoi) OR (tay hoi)). hieu van cac ((xac va) OR (hoc va)) hanh vi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach thieu van ((xay hoi) OR (tay hoi)). hieu van cac ((xac va) or (hoc va)) hanh vi cua tre~".
• Adding a wildcard symbol may retrieve word variants: so sach thieu van ((xay hoi) OR (tay hoi)). hieu van cac ((xac va) or (hoc va)) hanh vi cua tre*.