Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
te sach » toc sach
van cac » van hac, van cau, van bac
cac duc » cac du, cao duc, cac dac
va tinh » may tinh
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
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.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach y nang ((x hoi) or (o hoi)). hieu van cac duc ((va tinh) or (ban thanh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y nang ((x hoi) OR (o hoi)). hieu van cac duc ((va tinh) OR (ban thanh)) dai cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach y nang ((x hoi) or (o hoi)). hieu van cac duc ((va tinh) or (ban thanh)) dai cua tre*.