Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
so sach » bo sach, co sach, hoc sach
tinh da » tinh va, tinh gia, tinh lao
tinh di » tinh doi, trinh di, tin di
van cac » van hac, van cau, van bac
va nang » van nang, da nang, cam nang
so sanh » do sanh
cua tre » cua te, cuu tre, cua triet
cac tu » cac thu, cach tu, cac du
x hoi » xa hoi, o hoi, x ho

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) OR (so sanh)) va nang x hoi. hieu van cac tu va ((tinh di) OR (tinh da)) cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) or (so sanh)) va nang x hoi. hieu van cac tu va ((tinh di) OR (tinh da)) cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (so sanh)) va nang x hoi. hieu van cac tu va ((tinh di) OR (tinh da)) cua tre*.