Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh hai » thanh phan, thanh hoa, thanh san
phan duc » pham duc, phan tu, phan dau
tu sach » thu sach, su sach, te sach
co sach » bo sach, cuon sach, hoc sach
hai cua » thai cua, dai cua, hoi cua
hieu ve » hieu va, hieu van
duc van » duc va, duc tan, duc manh
cua te » cua tu
nang o » nang co, nang ho, nang ro
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: ((tu sach) or (co sach)) ky nang o hoi. ((hieu ve) or (hieu qua)) phan duc van thanh hai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (co sach)) ky nang o hoi. ((hieu ve) OR (hieu qua)) phan duc van thanh hai cua te.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (co sach)) ky nang o hoi. ((hieu ve) or (hieu qua)) phan duc van thanh hai cua te*.