Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
sach van » sach han, sach va, bach van
van nang » van quang, van ban, van dong
truc van » truc va, thuc van, truc ban
thanh de » hanh de, thanh ve, thanh do
so sach » so sanh, bo sach, co sach
hieu ve » hieu va, hieu van
cuu tre » cua tre, cau tren, cau treo
mo hoc » mon hoc, co hoc
ve cau » ke cau, va cau, ve cac
de cuu » de cua
o hoi » co hoi, o hoc, o hai

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 van nang ((o hoi) or (mo hoc)). hieu ve cau truc van thanh de cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach van nang ((o hoi) OR (mo hoc)). hieu ve cau truc van thanh de cuu tre.
• Adding a wildcard symbol may retrieve word variants: so sach van nang ((o hoi) or (mo hoc)). hieu ve cau truc van thanh de cuu tre*.