Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh ve » hanh ve, thanh va, thanh vien
su sach » so sach, vu sach
vuc van » duc van, luc van, thuc van
sach vu » sach va, sach tu, sach uu
su tien » su kien, su hien, tu tieng
vu nang » vuc nang, va nang, vu dang
va dao » ca dao
o hoc » co hoc, mo hoc, so hoc
o hoi » co hoi, o hai, o hoa
ve su » va su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach vu nang ((o hoi) OR (o hoc)). hieu ((va dao) or (va cac)) vuc van thanh ve su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach vu nang ((o hoi) OR (o hoc)). hieu ((va dao) OR (va cac)) vuc van thanh ve su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach vu nang ((o hoi) OR (o hoc)). hieu ((va dao) or (va cac)) vuc van thanh ve su tien".
• Adding a wildcard symbol may retrieve word variants: su sach vu nang ((o hoi) OR (o hoc)). hieu ((va dao) or (va cac)) vuc van thanh ve su tien*.