Perhaps you should try some spelling variations:
thanh hoi » thanh hoai, thanh hoa, thanh hai
ban thanh » ban hanh, ban hang
te sach » toc sach
hoi cua » hoi chuc
dua ban » dia ban, cua ban, qua ban
cua tre » cua te, cuu tre, cua triet
ve cach » va cach, ve canh
y nang » ky nang, ly nang, v nang
ve cac » va cac, vien cac
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: te sach y nang ((x hoi) OR (o hoi)). hieu ((ve cach) OR (ve cac)) dua ban thanh hoi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach y nang ((x hoi) OR (o hoi)). hieu ((ve cach) or (ve cac)) dua ban thanh hoi cua tre~".
• Adding a wildcard symbol may retrieve word variants: te sach y nang ((x hoi) OR (o hoi)). hieu ((ve cach) or (ve cac)) dua ban thanh hoi cua tre*.