Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh de » hanh de, thanh ve, thanh do
truc van » truc va, thuc van, truc ban
sach van » sach han, sach va, bach van
so sach » so sanh, bo sach, co sach
cua tre » cuu tre, cua triet, dua tren
hieu ve » hieu va, hieu van
ve cau » ke cau, va cau, ve cac
cua te » cua tu
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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 van ban ((x hoi) OR (o hoi)). hieu ve cau truc van thanh de ((cua tre) OR (cua te))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach van ban ((x hoi) OR (o hoi)). hieu ve cau truc van thanh de ((cua tre) or (cua te))~".
• Adding a wildcard symbol may retrieve word variants: so sach van ban ((x hoi) OR (o hoi)). hieu ve cau truc van thanh de ((cua tre) or (cua te))*.