Perhaps you should try some spelling variations:
van nang » van quang, van ban, van dong
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
tinh di » tinh doi, trinh di, tinh da
va tinh » may tinh
van cac » van hac, van cau, van bac
cua tre » cua te, cuu tre, cua triet
so sanh » do sanh
cac tu » cac thu, cach tu, cac du
di cua » dai cua, doi cua, de cua
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

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